Believe me its something which is almost a daily thought, I have read 3 of the Holy Books, Koran, Torah, and the Bible, I am not a Christian or even religious so I don't myself have the understanding to answer that question, all the arguments, for God, in whatever form, can't explain it, they say that God simply existed, but for us, everything has a beginning and an end, so thats one of the reasons why we find it difficult to comprehend that thought, the idea of space, with no beginning or end, the idea of God with no beginning or end.
It requires us to have faith, for example for many centuries the general populus believed that the earth was flat, the reason being that they didn't have the means to prove their theories, all theories need faith, and a theory continues to exist until it is either proved right or wrong. If wrong then a new theory is developed.
(on a side note the reason I post links is for the those that wish to find out a little bit more about arguments or points that I raise in my post.)