Caesar=Caesar...God=God!!
Except that no one ever considered Caesar to be the representative of Jesus on the earth.
If so, then there's a couple problems.
For one thing, a great number of popes never acted like Christ. One would expect more integrity from men who name the name of Christ in such a manner. It is clear that there is no fear of God in the men who lay claim to such an office and make such a mockery of it.
Another issue is for lay Catholics. Criticizing the pope then becomes equivalent to criticizing Jesus and it also becomes criticizing the work of the Holy Spirit in guiding the college of cardinals in selecting the new pope, if indeed He does.
I have asked in the past if that is the case, that the Holy Spirit guides them in the selection of the new pope and have yet to get an answer.