Titus 3:5
Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost;
Primary
What this passage establishes
Salvation rests on God’s mercy through the washing of regeneration and renewal of the Holy Ghost.
Why it matters in the argument
The apostolic record consistently treats repentance, water baptism, and Spirit reception as the commanded response to the gospel rather than optional religious accessories.
Apostolic connection
The singular name of Matthew 28:19 is enacted throughout Acts by baptism in the name of Jesus Christ, the revealed saving name.
Common misunderstanding
Baptism does not earn grace. It is a faith-response in which the believer obeys Christ, identifies with His death and burial, and calls on His name.
How to use it in conversation
Read the command, then show the apostles carrying it out. Let Acts interpret how Matthew 28:19 was understood.