We are studying Richard Taylor in my Philosophy of Religion class and as a theist, he is contented with the idea of an infinite and eternal universe, assuming that the universe is dependent on God for its existence.
In his book entitled Metaphysics, he explains:
"People tend to think that creation -- for example, the creation of the world by God -- means creation in time, from which it of course logically follows that if the world had no beginning in time, then it cannot be the creation of God. This, however, is erroneous, for creation means essentially dependence, even in Christian theology. If one thing is the creation of another, then it depends for its existence on that other, and this is perfectly consistent with saying that both are eternal, that neither ever came into being, and hence, that neither was ever created at any point of time. Perhaps an analogy will help convey this point. Consider, then, a flame that is casting beams of light. Now there seems to be a clear sense in which the beams of light are dependent for their existence upon the flame, which is their source, while the flame, on the other hand, is not similarly dependent for its existence upon them. The beams of light arise from the flame, but the flame does not arise from them. In this sense, they are the creation of the flame; they derive their existence from it. And none of this has any reference to time; the relationship of dependence in such a case would not be altered in the slightest if we supposed that the flame, and with it the beams of light, had always existed, that neither had ever come into being.
 Now if the world is the creation of God, its relationship to God should be thought of in this fashion; namely, that the world depends for its existence upon God, and could not exist independently of God. If God is eternal, as those who believe in God generally assume, then the world may (though it need not) be eternal too, without that altering in the least its dependence upon God for its existence, and hence without altering its being the creation of God. The supposition of God's eternality, on the other hand, does not by itself imply that the world is eternal too; for there is not the least reason why something of finite duration might not depend for its existence upon something of infinite duration -- though the reverse is, of course, impossible."
This material gets me thinking, If the universe need not even have a beginning for God to exist, why are young earth creationists so opposed to the idea that the earth was not created in six days?
Furthermore, what are atheists attempting to prove by stating that the universe is eternal? That still wouldn't give a sufficient explanation for why and how it exists.