Baptism is an act of obedience required of all who believe the gospel. It is a bodily immersion in, and not a face-sprinkling or head pouring, with water. Its administration to infants, in any form, is unauthorized and useless;1 it is only enjoined on those who have intelligence enough to believe the glad tidings of the Kingdom of God and the things concerning the name of Jesus Christ. To such it is a means of that present union with Christ which is preparatory to perfect assimilation at the resurrection, It is, therefore, necessary to salvation.

Go ye into all the world, and preach the gospel to every creature. He that believeth and is baptized2 shall be saved; but he that believeth not shall be damned.(Mark 16:15-16).

Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God. (John 3:5).

Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ...Then they that gladly received his word were baptized (Acts 2:38-41).

When they believed (people of Samaria) Philip preaching the things concerning the kingdom of God, and the name of Jesus Christ, they were baptized, both men and women. (Acts 8:12).

He commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him. (Acts 8:38).

Paul (after his conversion) arose, and was baptized. (Acts 9:18).

Lydia was baptized, and her household (Acts 16:15).

The keeper of the prison (at Philippi)... was baptized, he and all his, straightway...believing in God with all his house (Acts 16:27, 33-34).

When they (twelve men at Ephesus) heard this, they were baptized in the name of the Lord Jesus. (Acts 19:5).

The like figure whereunto even BAPTISM DOTH ALSO NOW SAVE US (not the putting away of the filth of the flesh, but the answer of a good conscience toward God,) by the resurrection of Jesus Christ: (1 Peter 3:21).

Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? 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. For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection: (Romans 6:3-5).

As many of you as have been baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise. (Galatians 3:27-29).

1 The claims of children to a religious standing irrespective of intelligence and faith are generally founded on Matthew 19:14: Jesus says, "Suffer (allow) little children, and forbid them not, to come unto me: for of such is the kingdom of heaven." This saying of Christ's. however, can mean nothing more than his other sayings: "Except ye be converted, and become as little children, ye shall not enter into the kingdom of heaven." (Matthew 18:3); "Verily I say unto you, Whosoever shall not receive the kingdom of God as a little child, he shall not enter therein." (Mark 10:15). Paul expresses the same idea: "In malice, be ye children" (1 Corinthians 14:20). If Christ's words in Matthew 19 are to be construed literally, they would amount to this: that the kingdom of God is to be made up of babies and children, and that, therefore, men and women would find no place. His real meaning is that the kingdom is reserved for those of childlike disposition. These, in the language of Scripture, are "babes and children." Hence, Jesus, speaking of his disciples, says, "I thank thee, O Father, that Thou hast hid these things from the wise and prudent, and hast revealed them unto babes" (Luke 10:21). Again speaking to them, he says, "Little children, yet for a little while I am with you" (John 13:33).

2 Baptizo is used in both Testaments in the sense of immersion, but never in the sense of sprinkling or pouring. The word baptize is not an English word, but is really an English form of the Greek word baptizo: which is not translated, but transferred into our language by the word baptize. Had baptizo been translated, as it could and should have been, there would at this time be no controversy on this subject - Malcolm's Bible Dictionary.
Prof. Stewart says, baptizo means dip, plunge, or immerse in any liquid. It may be added, "especially in the dyeing art, with a view to produce a change of colour."