If you're speaking of years prior to the film, I've never seen that. Yes, his dad is a dangerous man, and yes, his wife agrees with him. And no, I've seen nothing to indicate he's senile. Aside from Mel's assertation that he's all there, he was perfectly coherant in his radio (as I noted earlier, I made a point of listening) and print interviews. Including less "mainstream" interviews I've both heard and read. His opinions in 2003 were perfectly consistant with everything he's said for at least the last couple decades.
You are correct SJackson, there has never been anything prior The Passion about Mel Gibson and his father's beliefs. It was only until The Passion came out that they tried to align him with his father's beliefs.