OK, it's time to wrap this up! It may be a long post, but it all needs to be said together. I will explain with the ability the Lord has given me, which is not saying much, for the Lord has little to work with in me.
In explaining what is involved in the faith of our salvation, Paul told us In Eph. 4 there is one body, one spirit, one Lord, one faith, one baptism, and one Father. Some say this one baptism is water baptism, and some say this is the spiritual baptism taking place in the heart of man at the moment of salvation. So let's go to the Scripture and find out.
At Pentecost in Acts 2 the Holy Spirit came in a new dimension, the Scripture says, in a new and living way. The apostles and those with them were filled with the Holy Spirit and spoke in tongues. This is when the Holy Spirit came to dwell in man permanently by the promise of Christ.
John 14:15-20
15 If ye love me, keep my commandments.
16 And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
17 Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
18 I will not leave you comfortless: I will come to you.
19 Yet a little while, and the world seeth me no more; but ye see me: because I live, ye shall live also.
20 At that day ye shall know that I am in my Father, and ye in me, and I in you.
Notice the bold. Jesus said, "I will come unto you." He said He would pray and the Father would sent the Comforter (the Holy Spirit) to abide with us forever, and then He said "I will come unto you."
Then He said, "you are in me, and I in you." It's obvious Christ is not speaking of physically coming and being in us, but spiritually. So we see here that not only is the Holy Spirit dwelling in us, but Christ is also dwelling in us.
Paul said in Galatians 2:20, I am crucified with Christ, never the less I live, yet not I, but Christ lives in me. So we see that both the Holy Spirit and Christ take residence in the heart and spirit of the believer.
Do you remember Jeremiah saying that the day would come when the Lord would circumcise the heart of man? The circumcision of the foreskin of man would turn to the circumcision of the heart. This is the regeneration of man to salvation. It is Christ coming into the heart of man and living in him, which was hidden from us in the Old Testament, but revealed by Paul in the New Testament.
Look closely at what Paul says in Col. 2:10-13.
10 "And ye are complete in him, which is the head of all principality and power:
11 In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
12 Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;"
The words of Jeremiah were fulfilled in Christ! We are circumcised "through the faith of the operation of God."
In vs. 12, "buried with Him in baptism" does this sound familiar?
Rom. 6:3-5
3 "Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death?
4 Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.
5 For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection:"
The "baptism into Christ" is revealed to us through Paul to be what Jeremiah prophesied so long ago as the "circumcision of the heart." It is the spiritual baptism of regeneration that takes place in the heart of man at the moment of salvation.
This is the "One Baptism" that Paul speaks of that is concerning our faith and salvation.
So what is the purpose of water baptism? Peter explained that in 1 Peter 3:21. Water baptism is the "like figure" the symbol of our spiritual baptism. The expression of our inward baptism that took place in the heart at conversion.