Why are theists so keen on using logical fallacies when arguing for the existence of God or attacking  atheists?

I don't think I am, pard.  Every year millions experience God for themselves.  You should, too.  It's the logical thing to do.  Don't bother moving the goalposts.  It's more evidence than you have to shore up your fantasy that there is no God.

 Well lets face it they dont really have any other alternative, do they. Since theists cant prove their god at all... And atheists only refuse to believe that deity exists At all.

They don't have facts or proof, they have to resort to fallacies, insults, harassment, and bullying.

I'll give it to you that some arguments for God are fallacious.

I'll also note that many atheists arguments against God are nothing but logical fallacies.

So if you want to critique any argument for, or against, God then you need to bring that one to the table.

Ambiguous generalizations (such as this "question") are also fallacious.

Atheists too indulge in logical fallacies.  One of their favorites is the "straw man", or more accurately, the "straw god" fallacy.  Even Bertrand Russell used this fallacy with  his "flying teapot" analogy.

It's not that they're particularly keen on using logical fallacies, it's just that they don't really have a choice. 

The atheist mind think falsehoods, fallacies, and fantasies are truth, fact, and reality.  Your question merely proves this fact.

Since they have no proof to present that God exists that's all thery have to fall back upon.

...he or she asked, ironically employing the logical "fallacy of many questions".

More likely using Heb. 11:1, 6 and Romans 10:17.