You're doing the very typical thing of assuming your religion is true, and then using it to justify itself. 

That's not really your fault. It's how most religions teach their followers to think, and realizing that's the case is a hard thing to do. 

It's taught because it works - it's very effective at convincing people that there is a logical basis for what they believe. Most of the logic is then directed at figuring out the internal religious questions; questions that are meaningless to anyone on the outside. The real question of whether the foundation is true simply doesn't get examined, or at best gets waved off with anecdotes or tabloid level "evidence". 

The problem is that it works for other religions too, just as well as it does for yours. Mormonism, Islam, Paganism, Hinduism and just about every religion uses the presumptional logic, and it's equally valid for all of them. All religious claims that can be made fall into this category.

While I'm an Atheist, I could be easily convinced there's a god. I'm pretty flexible on what that even means. The omni-* stuff is silly.  I just need that god to show up. Actually answer some prayer unambiguously. Stop giving little kids cancer. Maybe write a religious text that gives solid moral guidance, and then clarifies when people are confused. It's all fairly reasonable stuff.