There are conditions for getting white clothes
In the Old Testament we can read about God’s instructions for how the israelites were supposed to cleanse themselves. God didn’t use a magic wand to cleanse them but THEY had to make sure to arrange things in such a way that they could be declared rightfully purified and cleansed by God. Whoever wanted to be cleansed had to wash both himself and his clothes, and not until then could he come into the camp. This actually works as a good picture of the requirements for entering the kingdom of God, because filthy sinners are not able to enter his kingdom but only those who are cleansed from their sins and considered righteous.
Leviticus 14:8 And he that is to be cleansed shall wash his clothes, and shave off all his hair, and wash himself in water, that he may be clean: and after that he shall come into the camp, and shall tarry abroad out of his tent seven days
Numbers 31:24 And ye shall wash your clothes on the seventh day, and ye shall be clean, and afterward ye shall come into the camp.
Numbers 8:21 21 And the Levites were purified, and they washed their clothes; and Aaron offered them as an offering before the Lord; and Aaron made an atonement for them to cleanse them.
In the book of Zacharia, we can read about Zacharia seeing Joshua, the high priest, standing before the angel of the Lord in filthy garments. The filthy garments symbolise bad deeds, and these bad deeds/iniquities were removed from Joshua and he was clothed with new garments. Joshua was also told about the conditions involved for being able to judge the house of the Lord and to be able to keep his courts. So a certain task was offered to Joshua, but then he must make sure to walk in God’s ways and keep his commandments. This is something that WE must accomplish and something that God doesn’t do for us.
Zacharia 3:1 And he shewed me Joshua the high priest standing before the angel of the Lord, and Satan standing at his right hand to resist him.2 And the Lord said unto Satan, The Lord rebuke thee, O Satan; even the Lord that hath chosen Jerusalem rebuke thee: is not this a brand plucked out of the fire?3 Now Joshua was clothed with filthy garments, and stood before the angel.4 And he answered and spake unto those that stood before him, saying, Take away the filthy garments from him. And unto him he said, Behold, I have caused thine iniquity to pass from thee, and I will clothe thee with change of raiment.5 And I said, Let them set a fair mitre upon his head. So they set a fair mitre upon his head, and clothed him with garments. And the angel of the Lord stood by.6 And the angel of the Lord protested unto Joshua, saying,7 Thus saith the Lord of hosts; If thou wilt walk in my ways, and if thou wilt keep my charge, then thou shalt also judge my house, and shalt also keep my courts, and I will give thee places to walk among these that stand by.
Just like the angels, Jesus in his translated/perfected form is often described as a man with shiny white clothes:
Rev. 1:12 And I turned to see the voice that spake with me. And being turned, I saw seven golden candlesticks;13 And in the midst of the seven candlesticks one like unto the Son of man, clothed with a garment down to the foot, and girt about the paps with a golden girdle.14 His head and his hairs were white like wool, as white as snow; and his eyes were as a flame of fire;15 And his feet like unto fine brass, as if they burned in a furnace; and his voice as the sound of many waters.16 And he had in his right hand seven stars: and out of his mouth went a sharp twoedged sword: and his countenance was as the sun shineth in his strength.
Matt 17:1 And after six days Jesus taketh Peter, James, and John his brother, and bringeth them up into an high mountain apart,2 And was transfigured before them: and his face did shine as the sun, and his raiment was white as the light.
Mark 9:3 And his raiment became shining, exceeding white as snow; so as no fuller on earth can white them.
Apg. 10:30 And Cornelius said, Four days ago I was fasting until this hour; and at the ninth hour I prayed in my house, and, behold, a man stood before me in bright clothing,31 And said, Cornelius, thy prayer is heard, and thine alms are had in remembrance in the sight of God.32 Send therefore to Joppa, and call hither Simon, whose surname is Peter; he is lodged in the house of one Simon a tanner by the sea side: who, when he cometh, shall speak unto thee.
Matt 28:1 In the end of the sabbath, as it began to dawn toward the first day of the week, came Mary Magdalene and the other Mary to see the sepulchre.2 And, behold, there was a great earthquake: for the angel of the Lord descended from heaven, and came and rolled back the stone from the door, and sat upon it.3 His countenance was like lightning, and his raiment white as snow:
Lukas 24: 1 Now upon the first day of the week, very early in the morning, they came unto the sepulchre, bringing the spices which they had prepared, and certain others with them.2 And they found the stone rolled away from the sepulchre.3 And they entered in, and found not the body of the Lord Jesus.4 And it came to pass, as they were much perplexed thereabout, behold, two men stood by them in shining garments:
Johannes 20:12 And seeth two angels in white sitting, the one at the head, and the other at the feet, where the body of Jesus had lain.
The two angels who were in and near Jesus’ grave (some accounts focus only on one of the angels) could be the same ones as the two men/angels in Acts 1:10:
Apg 1:9 And when he had spoken these things, while they beheld, he was taken up; and a cloud received him out of their sight.10 And while they looked stedfastly toward heaven as he went up, behold, two men stood by them in white apparel;11 Which also said, Ye men of Galilee, why stand ye gazing up into heaven? this same Jesus, which is taken up from you into heaven, shall so come in like manner as ye have seen him go into heaven.
John received a revelation from God and was told that God actually sees the works of man even if it concerns believers (and the sins are not hidden behind the blood of Jesus), and also that the church in Sardis should be watchful to strengthen the things which are about to die. Why are they about to die? Because their works are not perfect before God. They are told to repent in order to avoid the risk of dying. We are also told that there are some individuals in the church of Sardis who had not defiled their clothes, and that whosoever overcomes (that is the one who endures to the end) will be dressed in white garments and his name will not be blotted out of the book of life, but will be acknowledged by the Father and the angels. 
Rev. 3:1 And unto the angel of the church in Sardis write; These things saith he that hath the seven Spirits of God, and the seven stars; I know thy works, that thou hast a name that thou livest, and art dead.2 Be watchful, and strengthen the things which remain, that are ready to die: for I have not found thy works perfect before God.3 Remember therefore how thou hast received and heard, and hold fast, and repent. If therefore thou shalt not watch, I will come on thee as a thief, and thou shalt not know what hour I will come upon thee.4 Thou hast a few names even in Sardis which have not defiled their garments; and they shall walk with me in white: for they are worthy.5 He that overcometh, the same shall be clothed in white raiment; and I will not blot out his name out of the book of life, but I will confess his name before my Father, and before his angels.
In the same chapter we can read that God is also aware of the works in the church of the Laodiceans, and the same thing applies there that the deeds play a big role for their salvation. The church members might very well have believed in God and the offer that Jesus made for them, but this doesn’t save them if they are lukewarm och don’t show the works that God expects to find in them. The church gets the advice to buy gold from God which is tried in fire, and in that way get enough money to buy white clothes. This is something that God will not force us to do, nor will he do it for us. Had it been up to God of course he would dress up every single human being in white clothes (he doesn’t want anyone to perish), but naturally he won’t clothe unrepentant sinners with white garments because of the conditions he has for salvation.
Rev. 3:14 And unto the angel of the church of the Laodiceans write; These things saith the Amen, the faithful and true witness, the beginning of the creation of God;15 I know thy works, that thou art neither cold nor hot: I would thou wert cold or hot.16 So then because thou art lukewarm, and neither cold nor hot, I will spue thee out of my mouth.17 Because thou sayest, I am rich, and increased with goods, and have need of nothing; and knowest not that thou art wretched, and miserable, and poor, and blind, and naked:18 I counsel thee to buy of me gold tried in the fire, that thou mayest be rich; and white raiment, that thou mayest be clothed, and that the shame of thy nakedness do not appear; and anoint thine eyes with eyesalve, that thou mayest see.19 As many as I love, I rebuke and chasten: be zealous therefore, and repent.20 Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me.21 To him that overcometh will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne.
In the same book we can read about twenty-four elders in white raiment and with golden crowns on their heads, and also about a great multitude with white robes standing before the throne and the lamb. We are told what kind of crowd this is and why they are wearing white clothes. These people are the ones who have come out of the great tribulation under the rule of Antichrist, and who have washed their clothes and made them white in the blood of the lamb. We wouldn’t be able to get cleansed apart from 1) the blood of the Lamb and 2) our repentance, faith and obedience.
Rev.4:4 And round about the throne were four and twenty seats: and upon the seats I saw four and twenty elders sitting, clothed in white raiment; and they had on their heads crowns of gold.
Rev. 7:9 After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands;10 And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.11 And all the angels stood round about the throne, and about the elders and the four beasts, and fell before the throne on their faces, and worshipped God,12 Saying, Amen: Blessing, and glory, and wisdom, and thanksgiving, and honour, and power, and might, be unto our God for ever and ever. Amen.13 And one of the elders answered, saying unto me, What are these which are arrayed in white robes? and whence came they?14 And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.15 Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.16 They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat.17 For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of waters: and God shall wipe away all tears from their eyes.
Rev. 6:9 And when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held:10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?11 And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants also and their brethren, that should be killed as they were, should be fulfilled.
Rev. 19:7 Let us be glad and rejoice, and give honour to him: for the marriage of the Lamb is come, and his wife hath made herself ready.8 And to her was granted that she should be arrayed in fine linen, clean and white: for the fine linen is the righteousness of saints.
Rev. 20:4 And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
We also have the well known parable in Matthew 22, about the king who prepared a wedding banquet for his son. Some people who were on the guest list and presumed to come still declined the invitation when they were requested to go. Instead others were invited. One particular person accepted the invitation and also went to the wedding banquet BUT neglected to wear wedding clothes so was kicked out. It was the guests’ own responsibility to make sure they were dressed in proper wedding clothes. So thanks to this parable we can see that 1) people were able to refuse to accept the invitation despite that they were expected to go, and 2) people were able to make the choice to accept the invitation, and they also went, BUT were still kicked out of the banquet because they were not properly dressed which was their own fault and a huge mistake, and 3) people who accepted the invitation, and who went to the banquet, AND who were properly dressed, were the ones who eventually could take part of all the blessings of the party that ALL were invited to.
Matt. 22:9 Go ye therefore into the highways, and as many as ye shall find, bid to the marriage.10 So those servants went out into the highways, and gathered together all as many as they found, both bad and good: and the wedding was furnished with guests.11 And when the king came in to see the guests, he saw there a man which had not on a wedding garment:12 And he saith unto him, Friend, how camest thou in hither not having a wedding garment? And he was speechless.13 Then said the king to the servants, Bind him hand and foot, and take him away, and cast him into outer darkness, there shall be weeping and gnashing of teeth.
