Plenty of apologists, such as William Lane Craig, believe that atheism leads towards nihilism, which can be defined as a philosophy that asserts existence and life are without any meaning whatsoever. This is presumably due to the belief that since God created humans for a purpose, that gives our life meaning. From this view, however, I fail to see how the argument doesn't apply to God, as well.
God was not created for any purpose because, well, he wasn't created. He has existed always; He's the last link in the causal chain. This means, that by this argument, God's existence must have no purpose, and assuming that God is a reasonable fellow, he should accept the philosophy of nihilism. If this be the case, we can also see that the purpose that God created us for is arbitrary and absurd, thus we must also accept nihilism even in a theistic world.
Any argument against this, seems to me, to also be favorable to the argument in favor of non-theistic arguments against nihilism as well, which negates any arguments against atheism that apply the false assumption that meaning can only exist with God. Suppose God creates his own purpose. Well, suppose that man creates his own, much like Sartre and other existentialists suggest. Suppose God is just innately endowed with meaning. Well, again, suppose that man, either through inheritance of certain traits or the influence of the environment, is endowed with certain innate drives that give his life meaning. Nothing, as far as I can see, can save only God from nihilism.