en_tn_lite_do_not_use/rom/16/18.md

Christ, but their own stomach

The words "they serve" are understood from the previous phrase. This can be expressed as a separate sentence. Alternate translation: "Christ. Rather, they serve their own stomach" (See: rc://en/ta/man/translate/figs-ellipsis)

but their own stomach

Here "stomach" is a metonym that refers to physical desires. Serving there stomach represents satisfying their desires. Alternate translation: "but they only want to satisfy their own selfish desires" (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-metaphor)

By their smooth and flattering speech

The words "smooth" and "flattering" mean basically the same thing. Paul is emphasizing how these people are deceiving believers. Alternate translation: "By saying things that seem to be good and true" (See: rc://en/ta/man/translate/figs-doublet)

they deceive the hearts of the innocent

Here "hearts" is a metonym for the minds and inner beings of people. Alternate translation: "they deceive the innocent believers" (See: rc://en/ta/man/translate/figs-metonymy)

innocent

This refers to those who are simple, inexperienced, and naive. Alternate translation: "those who innocently trust them" or "those who do not know these teachers are fooling them"