What does it mean to serve your own appetites?

In Romans 16:18 Paul writes that those who sow divisions and spread heresy in the church do not serve our Lord Christ, but their own appetites, and by smooth talk and flattery deceive the hearts of the naive. The strength of any aberrant doctrine always depends on its imposing arguments and a pleasing presentation. It is the tongue that misleads. The weakness of aberrant doctrine lies in the fact that its proponents do not submit themselves to the Lord Christ, but remain servants of their own appetites. The Greek word Paul uses here, koilia, refers to the belly cavity, as the location of the stomach and the intestines. It is the seat of feelings. False teachers allow themselves to be led by their own preferences and feelings. They regard their own inner self as more important than the external authority of the heavenly Lord. Paul therefore describes the reality that subjective human feelings and impulses often make subjecting to the authority of God and his Son difficult. Precisely because deviation from doctrine plays on the naive feelings of the ignorant, it is good to distance oneself in advance from everyone who deviates from established doctrine.¹