Diodorus of Tarsus/Diodore of Tarsus’s asking and praying did not mean baptismal vows
There seems to be a rather unfortunate mistake held by some people, that Diodorus of Tarsus's writing "to pray and to ask" is in reference to baptismal vows. HOWEVER, a reading of Diodorus of Tarsus shows that this is wrong, and that it is instead referencing asking God for the gift of salvation.
This is cleared up in two ways.
1st. Comparing what Diodorus of Tarsus, or some say Diodore of Tarsus in Romans 10 to earlier passages.
“Necessarily he set forth ‘those who call upon him.’ For God does not give grace without discernment, extending it even to those who are unwilling to offer so much to the Benefactor as at least to ask and pray with him. And lest anyone say that many fail to call upon the Lord Jesus out of ignorance rather than unbelief and ingratitude, he shows through what follows that God took away even the excuse of their ignorance, sending evangelists and heralds who urge and invite them to ask for the gift. Therefore he added what follows.” - Diodorus of Tarsus/Diodore of Tarsus, Romans 10:11-13.
Notice, he clarifies it is the gift of salvation that is being asked by the sinner to the Benefactor.
God is the benefactor.
“Instead of corresponding to the one sin of Adam, the gift was great and abundant and surpassed the sins of all by its love for mankind, which he teaches by adding: “For the judgment from one resulted in condemnation, but the gracious gift from many trespasses resulted in justification.” For he means to say that Adam’s sin was one, but nevertheless, being one, from one sin it condemned the many because they imitated Adam. But the gracious gift of the Lord was not measured against one sin, but against the sins of all, which were many. So delivering them from many trespasses, he brought them into justification. For in this is the abundance of grace, that it not only delivered from trespasses, but also guided them into righteousness.” - Diodorus of Tarsus/Diodore of Tarsus, Romans 5:16-17
The gift is salvific.
Study what he writes.
εὐαγγελιστὰς καὶ κήρυκας (evangelists and heralds/preachers)
ἄγνοιαν (ignorance) and ἀπιστίαν (unbelief)
προτρέποντας καὶ καλοῦντας εἰς τὴν τῆς δωρεᾶς αἴτησιν (urging and calling them to the asking/request of the gift)
αἰτῆσαι καὶ δεηθῆναι (to ask and to pray/beseech)
There is not a single water motif in the text, or anything linked to baptism.
2. He already distinguished between water baptismal vows and asking God to save you.
He says
“What kind of sin will not have dominion? That which was before baptism, which the grace of Christ forgives” - Diodorus of Tarsus/Diodore of Tarsus, Romans 6:12-14
We understand that grace is obtained through asking and praying. Grace is already obtained before baptism.
“Necessarily he set forth ‘those who call upon him.’ For God does not give grace without discernment, extending it even to those who are unwilling to offer so much to the Benefactor as at least to ask and pray with him. And lest anyone say that many fail to call upon the Lord Jesus out of ignorance rather than unbelief and ingratitude, he shows through what follows that God took away even the excuse of their ignorance, sending evangelists and heralds who urge and invite them to ask for the gift. Therefore he added what follows.” - Diodorus of Tarsus/Diodore of Tarsus, Romans 10:11-13.
Now, analyze his baptismal vows.
“What then shall we say?” he says. “Shall we continue in sin, so that grace may increase? By no means.” He added “By no means” safely. For those who sin maliciously are not worthy of forgiveness, but those who through carelessness and inattention receive the schemes of the devil, these are just to be pitied by God. “How shall we who died to sin still live in it?” Since those who are baptized confess that they have died to the world and renounced sin and the devil.” - Diodorus of Tarsus/Diodore of Tarsus, Romans 6:1-4
The baptismal vows are confessing to the world, and renouncing sin and the devil.
The αἰτῆσαι καὶ δεηθῆναι (to ask and to pray/beseech) is to God, not the world. It is a confession, not a profession.
