I think the following definition for “baptizo” from Kenneth Wuest is very clear and helpful when considering this great subject.
Kenneth Wuest in his writing in Romans in the Greek New Testament p96:
“Baptizo means the introduction or placing of a person or thing into a new environment or into union with something else so as to alter its condition or its relationship to its previous environment or condition.”
Developing this thought Wuest gives us more insight by the use of the word in Romans 6. The passage is detailed in its exposition but a valuable help to our understanding of the chapter.
He goes on to say regarding its usage in Romans 6:4
“It refers to the act of God introducing a believing sinner into vital union with Jesus Christ, in order that that believer might have the power of his sinful nature broken and the divine nature implanted through his identification with Christ in His death, burial and resurrection, thus altering the condition and relationship of that sinner with regard to his previous state and environment, bringing him into a new environment, the kingdom of God. God placed us in Christ when He died so that we might share His death and thus come into the benefits of that identification with Him, namely, be separated from the evil nature as part of the salvation He gives us when we believe. We were placed in a new environment, Christ. The old one was the First Adam in whom as our federal head we were made sinners and came under condemnation. In our new environment in Christ we have righteousness and life. Our condition is changed from that of a sinner to that of a saint.”
But we were not only placed in Christ by God the Holy Spirit in order that we might share His death and thus be separated from the evil nature, but we were placed in Him in order that we might share His resurrection and thus have divine life imparted to us. This Paul tells us in the words, “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.” The newness of life here does not refer to a new quality of experience or conduct but to a new quality of life imparted to the individual.
Romans 6 does not deal with the Christian’s experience or behaviour. Paul treats that in chapters 12-16. In this chapter the key word is machinery, the mechanics of the Spirit-filled life being Paul’s subject. The newness of life here refers, not to a new kind of life the believer is to live, but to a new source of ethical and spiritual energy imparted to him by God by which he is enabled to live the life to which Paul exhorts in Romans 12-16. “Walk is peripateo, “to order one’s behaviour, to conduct one’s self.” The word “should” (AV) throws us off the track. There is no moral obligation imposed here. We have a purpose clause in the subjunctive mode introduced by the purpose particle hina. That is, we shared Christ’s resurrection in order that we may order our behaviour in the power of a new life imparted.”
What a marvellous life we are brought into by baptism with the Holy Spirit! How essential it is for all of us to know and experience it.