I don't think this is the case. Hell, most of the time people don't bother looking closely at the lyrics of any given album. I can listen to Redemption or Theocracy without agreeing with their political and religious views. It's when those opposing viewpoints are expressed as obnoxiously as Mustaine's in this case that I draw the line.
I've always been a sucker for lyrics, because I like to see what makes people tick. That's probably one of the main draws for me to this genre. For instance, I've always thought Testament was cool, because of their political lyrics. They appealed to me even when I was an early teen due to this reason. Honestly, I've not looked at Redemption's lyrics and FatesFan will probably give me a hard time for that!

Now you have me intrigued, so I'll take a closer look.
And I have no idea what Dio said about Christianity, but he was probably right. BECAUSE HE'S DIO.
Let's just say that Dio was no way a Christian in any shape, form or fashion. I've listened and watched some interviews of him over the years, plus it's pretty obvious in some of his songs. With that said, I've always thought he's one of the most talented song writers...ever! Below are the lyrics to Jesus, Mary & The Holy Ghost, which is one example.
Prime time
Nursery rhyme
Did you see the teacher
Sister
Black and white
What she's gonna to do
They say eye for eye, tooth for tooth
But don't hurt your brother
Cross-road, overload
Oh, I, I testify
They just showed me Mary
She was stoned, stoned, danger zone
There was nothing in her eyes
And then there, there in the air
Nailed to the cross was Jesus
Cross-road, overload
Now I lay me down to sleep
Pray my soul to keep away
From the holy spirit, holy ghost
They're hiding in the dark
Oh, nightmare, electric chair
You might not get to heaven
Bad boys, shout for joy
Watch him to cry
Prime time
Nursery rhyme
Love just needs religion
Cross-road, overload
~Brian~