Baptism is not a charm or a magic spell. The Apostle Paul writes, referring to the Old Testament sacrament of circumcision:
For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: but he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God.
- Rom. 2:28-29
The same is true of baptism. There are many baptized outwardly and properly, with water, and in the name of the Trinity, who nevertheless have uncircumcised hearts - because they have no true saving faith in Christ. The Jews were commanded by God to circumcise their hearts (Deut. 10:16) but they proved themselves utterly unable to do so. Part of God’s wonderful New Covenant promise is that he will intervene to circumcise his people’s hearts (Deut. 30:6).
Our church, lamentably, sees many babies brought to the font, baptized in the name of the Father, and of the Son, and of the Holy Ghost, and yet, as evidenced by their subsequent lives of unbelief and sin, their hearts remain uncircumcised: they remain unregenerate, and the children of wrath.