"who are causing believers to argue with one another and to stop having faith in God"
## going beyond the teaching that you have learned ##
This can be translated as a new sentence: "They teach things that do not agree with the truth you have already learned."
## Turn away from them ##
"Stay away from them"
## but their own belly ##
Here "belly" refers to physical desires. Alternate translation: "but they only want to please their own selfish desires" (See: [[rc://en/ta/man/translate/figs-metonymy]])
## 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]])
## innocent ##
simple, inexperienced, and naive. Alternate translation: "those who innocently trust them" or "those who do not know these teachers are fooling them."