My boyfriend of two years wants to stop having sex to get closer to god. But we are already in a long distance relationship. I know that he honestly wants to get closer to god. But its not about us, its about him.

To top it off, a month ago he said he didn't want to rush getting married, now he wants to get married in 6 months. I love him so much but I greatly dislike being mentally tossed around.

He wants to get married so that he can have sex with you and not feel guilty.

I think you better talk more and get on the same page before you take that big step of marriage.

Maybe this newfound religious thing is what makes him want to only have sex with a wife, and not just a girl friend. Ask him.

If you are 100% sure that the issue is religion rather than him dipping his comb into other honey pots, I would suggest having a deep conversation with him about it. The religion and his move towards its sphere of influence suggests that there may be other issues that you either not aware of yet or have been kept from you so far. Most people go to God when they feel lost. Not when they feel fulfilled. God provides structure to those that often have very little of it available to them.
The only thing that is going to make this better for you is more communication. He is obviously going through something that is causing him to change his mind rapidly on issues like marriage and sex. This suggests a significant influence in his life that is outlining his interactions with you and his expectations of you. If you plan to stay with him, you will have to be prepared to also be married to whatever or whoever this influence is as well any other ideas they may have.
I know that were I in your shoes, conversation and a quick exit plan would be the first two things I try to get put together. You have a choice to make very soon. Stay who you are and hopefully be happy with that person, or change yourself to fit his image of what you should be. What ever choice you make, know that it will likely be the choice of whether to continue your relationship or end it when the dust settles.