He is a deeply religious man and his views are rooted in religious belief, the most powerful belief there is. I seriously doubt he has changed his views, he just wisened up to where the wind blows.
The rate at which public opinion has changed in favour of gay marriage, etc. over the past few decades could have only happened with a lot of people changing their mind. The shift happened way too fast for it to have been entirely down to old bigots dying off.
Beliefs can change based upon experiences and time. It's called wisdom.