I've always liked this quote

"Going to church doesn't make you any more a Christian than going to the garage makes you a car."
-Laurence J. Peter

I have also always like the following quote, ever since I heard it, years ago:

"A man convinced against his will, is of the same opinion still."
-unknown

There are similar quotes to this one as well, including the following:

"A man convinced against his will is not convinced."
-Laurence J. Peter

"He that complies against his will
Is of his own opinion still. "
~Samuel Butler, in Hudibras (Part iii. Canto iii. Line 547)