You could try by showing where Calvin was in error rather than just calling him a fraud.
Speaking of trying to argue with a "the gospel says... But I say...." type of argument, I find it humorous in light of the multiple commands not to bow before graven images or to communicate with the dead that you would claim that such commandments do not apply to your peculiar practices of bowing before statues and praying to saints.
In that sense your theology is nothing more than "the gospel says... but my pope says....". How are we supposed to argue with that?
I don't "just call" Calvin "a fraud". See for example, my recent 4320 and 4370 on this thread. When Calvin attempts ro reason from the gospel, he fails. When he simply tells us what he thinks, we have no more reason to listen to him than to the author of the daVinci Code.