Let's look at the two possibilities of Atheism and Theism (specifically, Monotheism). Most scientists agree that the evidence points towards the universe having a beginning at some point; that the universe has not existed infinitely. That's where the theory of the Big Bang comes in. There was once nothing, and in a "Big Bang" the universe exploded into existence. Many atheists believe in the Big Bang, I do as well. But suppose we are walking around outside and you hear a loud bang. You turn to me and ask, "What was that?" I reply, "A loud bang." You say, "Yes, but what caused it?" And I say "Nothing, it just happened." Would you believe me? Of course not, because this conclusion follows no logic. Everything that happens or has a beginning has a cause.
Monotheism is the most logical explanation for the origin of Life and the Universe. The Universe had a beginning and therefore was caused by something that existed before it. God, unlike the universe, has no beginning or end. God is infinite, He exists outside of time because He created time and infinitely existed before he created time. We are finite beings with finite lives and finite knowledge. Could we POSSIBLY be the most intelligent things in the universe?! Not only is that a scary thought, it is highly unlikely. There are SO many things that we as humans cannot even comprehend or begin to understand, yet we are so arrogant to thing we are the most superior or intelligent beings? You may say that its possible for there to be aliens with more understanding than us, and I agree, it is possible. But would they be the most intelligent? Would they understand everything? If they did, would that not make them gods? Humankind has proven its flawed state over and over again throughout history, so its not surprising that humans in out arrogance could think that we are the most powerful and most intelligent beings. "We are man! We answer to no one! Nothing could be smarter or stronger than us! We are at the top!" .... this attitude is a mark of humanity's blind arrogance.
Besides the existence of some sort of Creator God being the only logical explanation to the functioning universe, there is even greater evidence of Him existing as creator in Life. If the Big Bang happened randomly and chaotically, life would never have showed up! There would just be matter! Life is NOT easy to create. The possibility of all the building blocks of life to fall together in exactly the right way multiple times is statistically impossible. Life is VERY complex. For DNA to have accidentally been written and even single celled life-forms to have been created would be like a bunch of letters "accidentally" forming entire sentences that formed an entire story with a beginning, moving plot, and end. Books have authors, so does life. I think the idea of life happening by itself is a misunderstanding of the complexity of life. Evidence from biology and chemistry show us how even the smallest single celled organisms are so complex that them forming in the first place is a miracle in itself, just because it is so unlikely. It would be about as likely as a blind man searching the Sahara desert for a pre-marked grain of sand and successfully find it, twice. The conditions for life to exist are on a razor's edge too. If the Earth were one degree closer to the sun all life on the planet were burn up and die, if we were one degree further from the sun we would freeze.
I hope this has caused everyone to think about things a little more deeply.
For better information read books such as "Darwin's Black Box" and "The Case for a Creator." There are plenty of other books on the subject obviously, I just can't think of any more right now.