Because it fascinates him

Noel's said a couple of times that he doesn't really know exactly what he believes, but he likes the artistic image of god and religion.

When he writes those reference, the majority of them are sacrilegious......

I think we need to clarify the meanings of these terms:

Atheist = absence of a belief in God
Theist = presence of a belief in God
Agnostic = belief that we cannot know right now (or can never know) whether or not God exists

So you can be an agnostic atheist or an agnostic theist. Basically every atheist is an agnostic atheist. It's a myth perpetuated by anti-atheism types that atheist = faith in the non-existence of God. If you see no compelling reason to believe in God, you are an atheist.

Even if Noel was best friends with the Pope I don't think he would say. Most musicians don't speak on the matter because it might affect peoples perception of them if they don't share the same beliefs. He was brought up by an Irish mother so you better believe for a part of his life he was made to believe in God and go to Church on Sunday. It might have made him angry that he was forced to believe in religion and so writing rebellious rock and roll music would be a logical response for him as a songwriter. Look at his titles "Heathen Chemistry" "Don't Believe The Truth" and the monitor loop from DBTT tour repeating the words "You Don't Want To Believe" yet alot of his music has a religious aspect to it. One song he'll say "Lord Don't Slow Me Down" and in the next he'll say "Let The Lord Shine A Light On Me". Its supposed to be confusing because just like song meanings we're not meant to understand his view, we just take out of it what we want.