John Calvin Commentary Philippians 3:19

"whose end is perdition, whose god is the belly, and [whose] glory is in their shame, who mind earthly things." — Philippians 3:19 (ASV)

Whose end is destruction. He adds this so that the Philippians, appalled by the danger, may be all the more careful to be on their guard, so that they do not involve themselves in the ruin of these people. However, since such profligates, through outward display and various deceptions, often dazzle the eyes of the unsuspecting for a time, so that they are even preferred over the most eminent servants of Christ, the Apostle declares with great confidence that the glory with which they are now puffed up will be exchanged for disgrace.

Whose god is the belly. Since they urged the observance of circumcision and other ceremonies, he says that they did not do this out of zeal for the law, but to gain human approval and so that they could live peacefully and without trouble. For they saw that the Jews burned with fierce anger against Paul and those like him, and that proclaiming Christ in purity would inevitably arouse the same anger against themselves. Accordingly, seeking their own ease and advantage, they mixed in these corruptions to reduce the fierce opposition from others.