How does baptism save (Mark 16: 16: 1 Pet. 3: 21)?
In Rom. 10:9, two things are presented as necessary for salvation: “if thou shalt confess with thy mouth Jesus as Lord, and shalt believe in thine heart that God has raised him from among [the] dead, thou shalt be saved”. Salvation thus depends upon faith and confession. In v10, the apostle makes a distinction between the two, linking faith with justification, and salvation with confession: “For with [the] heart is believed to righteousness; and with [the] mouth confession made to salvation”. Faith, which is inward, results in righteousness before God; confession, which is outward, results in salvation before men (men can only take account of the outward).
Scripture also links confession (and therefore salvation) with baptism. Thus the Jews were baptised by John “in the Jordan, confessing their sins” (Mark 1: 5). They confessed their sins in baptism. In Mark 16: 16, both faith and baptism are said to be necessary for salvation: “He that believes and is baptised shall be saved”. Believing, which is inward, is before God; baptism, which is outward, is a confession before men. While the end of faith is the salvation of our souls (see 1 Pet. 1: 9), baptism has nothing to do with heaven or eternity. Hence Mark 16: 16 goes on to say that only “he that disbelieves shall be condemned”––nothing there about not being baptised. Baptism saves, but it is salvation on earth, before men.
In Col. 2: 11, 12, Paul parallels baptism with circumcision. No man was owned a Jew until circumcised - so much so that the Jews were called “the circumcision” (Acts 10: 45). A man might have faith in Jehovah, but only circumcision made him a Jew. Again, a man becomes a soldier by taking the oath of allegiance, but he is not recognised as such until he dons the uniform - it is that which separates him from civilians. Baptism has a similar effect, and thus even Paul’s sins had gone from God’s sight the moment he was converted, he was still told “et baptised, and have thy sins washed away, calling on his name” (Acts 22: 16). Outwardly, he was still associated with his former, sinful life––not until he was baptised was he publicly separated from his sins. Thus though a man might have faith in Christ, he cannot be recognised as a Christian as such until he puts on Christ in baptism. Hence: “as many as have been baptised unto Christ, have put on Christ” (Gal. 3: 27). Faith makes a person a believer, baptism a disciple (see Matt 28: 19)––in general terms, a disciple is a learner who outwardly identifies himself with a teacher and recognises his authority.
Thus baptism identifies me with Christ. It is “unto Christ Jesus” (Rom. 6: 3; see also Acts 2: 38, 19: 5). It makes me a subject of Christ’s Kingdom, the One to whom all power in heaven and on earth has been given (see Matt 28: 18). There I find complete protection for “The name of Jehovah is a strong tower: the righteous runneth into it, and is safe” (Prov. 18: 10) - those who take refuge there are saved. They separate themselves to the Saviour. There is no such thing as salvation without separation. Thus 2 Thess. 2: 13 speaks of “salvation in sanctification” (my emphasis), sanctification involving separation. It is when I am separated from what is against me that I am saved. (Hence the full thought of salvation awaits the setting up of the kingdom in power when Christ returns.) At the present time it is baptism that separates (and hence, saves me). Baptism saves me by cutting me off from what I was previously associated with, and bringing me under the care and authority of another––separation from and separation to. Israel in Egypt, sheltered by the blood, were safe from divine judgment but they only had salvation when they crossed the Red Sea (see Ex. 15: 2)––only then were they separated from all that was against them. They were “baptised unto Moses in the cloud and in the sea” (1 Cor. 10: 2)––separated to Moses, and brought under his authority. Similarly, “in [the] days of Noah while the ark was preparing, into which few, that is, eight souls, were saved through water: which figure also now saves you, [even] baptism” (1 Peter 3: 20, 21). Baptism is here identified with the water. The ark saved Noah’s family through the judgement waters, but those very same waters also saved them by separating them from all that merited judgment. As with the flood, so with baptism––it saves by separation.
Of course, baptism does not change me inwardly, but a “good conscience” would demand it. An unbaptised Christian is like a soldier without a uniform––displaying no allegiance to Christ, he can expect none in return (comp. Matt. 10: 33). In baptism, I reckon myself dead and buried with Christ. I have finished with my past life, come under the authority of Christ, and as one of His subjects, receive his daily protection and care - it is in that sense that baptism "saves".