If water baptism is a CONDITION to be met, along with to “believe,” then let the word of God say so in at least two or three places of scripture. Upon the mouth of two or three witnesses let every word be ESTABLISHED.
They may come up with one obscure verse, but that is not enough, according to the way Jesus instructed us to build doctrine.
The thing is, that
isn’t “how Jesus instructed us to build doctrine.” That, my friend, is a
tradition of men to interpret it that way. How did Jesus tell us to know what He taught? By listening to the apostolic teaching: “Jesus approached and said to them, “All power in heaven and on earth has been given to me. Go, therefore,* and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the holy Spirit, teaching them to observe all that I have commanded you.”" (Mt 28:18-20)
Again, Peter reminds us of this: “recall the words previously spoken by the holy prophets and the commandment of the Lord and savior through your apostles.” (2 Peter 3:2)
So, is this something for you to discern, yourself, based “on two or three witnesses”? No… it remains the province of apostolic teaching: “you have heard of the stewardship of God’s grace that was given to me for your benefit, [namely, that] the mystery was made known to me by revelation, as I have written briefly earlier. When you read this you can understand my insight into the mystery of Christ, which was not made known to human beings in other generations as it has now been revealed to his holy apostles and prophets by the Spirit… Of this I became a minister by the gift of God’s grace that was granted me in accord with the exercise of his power. To me, the very least of all the holy ones, this grace was given, to preach to the Gentiles the inscrutable riches of Christ, and to bring to light [for all] what is the plan of the mystery.” (Ephesians 3:2-9)
So… no “on the testimony of two or three”, but rather, in the following of apostolic teaching.
Baptism, likewise, has many citations. First and foremost is Jesus’ command, quoted above, in which teaching and baptism is what makes a person a disciple of Christ.
What makes us one Body in Christ? “We were all baptized by one Spirit so as to form one body” (1 Cor 12:13), such that we “are Christ’s body” (1 Cor 12:27).
But maybe baptism
isn’t important. Maybe it’s just something that’s nice to do, that simply washes us. Peter disagrees: “[Noah’s flood] prefigured baptism, which saves you now. It is not a removal of dirt from the body but an appeal to God.” (1 Peter 3:21)
(Incidentally, in my Bible, the verse referenced at Mt 18:17 is 1 Cor 5:3-4 – “I … have already, as if present, pronounced judgment on the one who has committed this deed, in the name of our Lord Jesus: when you have gathered together and I am with you in spirit with the power of the Lord Jesus, you are to deliver this man … so that his spirit may be saved on the day of the Lord.” So, the “two or three” referenced there is lived out by Paul in Corinth as a means of adjudicating a dispute.)