Where believer's baptism is practiced, the mode is almost always full immersion, the candidate briefly submerged entirely under water, on the reading that the Greek word baptizo itself means to dip or immerse and that the act pictures Paul's language of being buried with Christ and raised to new life. This sets it apart doubly from most other Christian bodies, which both baptize infants and typically do so by pouring or sprinkling rather than immersion.
The theological argument against infant baptism runs that baptism in the New Testament always follows repentance and personal faith, never precedes it, so an infant incapable of either should not receive the sign. Churches that hold believer's baptism commonly offer a service of infant dedication instead, presenting a child to God and the congregation without treating the act as baptism itself, reserving the ordinance for a later, conscious profession.
The practice remains one of the sharpest and most durable lines of division inside Christianity. Baptist, Anabaptist, Pentecostal and several Adventist and Restorationist bodies hold it; Catholic, Orthodox, Anglican, Lutheran, Reformed and Methodist churches baptize infants, understanding the act to convey grace or to mark a child's inclusion in the covenant community rather than to require prior faith, so that the same word, baptism, names two theologically different acts depending on which church performs it.