Romans 6:4

Therefore we are buried with him by baptism into death
The nature and end of baptism are here expressed; the nature of it, it is a "burial"; and when the apostle so calls it, he manifestly refers to the ancient and only way of administering this ordinance, by immersion; when a person is covered, and as it were buried in water, as a corpse is when laid the earth, and covered with it: and it is a burial with Christ; it is a representation of the burial of Christ, and of our burial with him as our head and representative, and that "into death"; meaning either the death of Christ as before, that is, so as to partake of the benefits of his death; or the death of sin, of which baptism is also a token; for believers, whilst under water, are as persons buried, and so dead; which signifies not only their being dead with Christ, and their communion with him in his death, but also their being dead to sin by the grace of Christ, and therefore ought not to live in it: for the apostle is still pursuing his argument, and is showing, from the nature, use, and end of baptism, that believers are dead to sin, and therefore cannot, and ought not, to live in it; as more fully appears from the end of baptism next mentioned;

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 the end of baptism is not only to represent the death and burial, but also the resurrection of Christ from the dead, which is here said to be "by the glory of the Father", some read the words, "unto the glory of the Father"; meaning either, that the Father might be glorified hereby; or that Christ, being raised from the dead, might enjoy glory with the Father, as he does in human nature; but rather the phrase expresses the means by which, and not the end to which, Christ was raised from the dead: and by the "glory of the Father" is meant, the glorious power of the Father, which was eminently displayed in raising Christ from the dead; and as baptism is designed to represent the resurrection of Christ, which is done by raising the person out of the water, so likewise to represent our resurrection from the death of sin, to a life of grace: whence it must be greatly incumbent on baptized believers, who are raised from the graves of sin by the power of Christ, to "walk in newness of life"; for since they are become new creatures, and have new hearts and new spirits given them, new principles of light, life, grace, and holiness implanted in them, and have entered into a new profession of religion, of which baptism is the badge and symbol, they ought to live a new life and conversation.