Where's the fallacy?

I showed you the fallacy. From

If P then Q

you cannot derive

If not P then not Q.

That's the fallacy. The sentence

If P then Q

Says what you can expect (namely, Q) when P is true. It doesn't say anything at all about when P is not true. I gave you an example showing quite plainly that this is a fallacious mode of argument. (I have a million of 'em, if that one didn't make sense.)

I don't know how much plainer I can put it.

As for your prayer thing, that's just silly. Do you want us to say, "Our Father who may or may not be in heaven"? We all act on knowledge/beliefs we're not certain of every day. I'm not certain that when I walk out of the door tomorrow morning, a meteor won't smash me all to hell. But I act as if it won't, because you can't go through life not doing anything just because you're not certain. Me, I'm not certain of anything. (This is one of the dangers of studying epistemology!) But you gotta live. You act on the things you believe to be true because, well, you believe them to be true. And that's all we've got.

You say you don't claim to be certain that God doesn't exist, but you live your life as though She doesn't. And that's as should be. I believe (but am by no means certain) that God exists, and live my life as if She does. Where's the problem?