He didn't call him a fascist....If you watch the whole video, you'll see Fox took what he said out of context. YouTube - Ron Paul on Fox & Friends (PT.1of2) 12-18-07 that's the full interview on Fox.

"We had a guest on a little while ago that thought it was inappropriate to be using religion for political purposes. What do you think of that?" This is the question he was referring to.

YouTube - Ron Paul on Mickelson 1 he explains it himself here.