It's surely similar to the chances of winning a lottery. Given that there are 200-400 billion stars in the Milky Way alone, whilst life is not probable in an individual solar system, it is probable given the number of opportunities that exist within the universe.
For me the key issue is one of proof, and this forms the basis for the disagreement.
Believers in God claim (rightly) that you cannot his prove his non-existence, and therefore he could exist.
Atheists and other non-believers claim that the onus of proof should be in terms of existence, rather...
I genuinely think you would benefit from reading The God Delusion. It does no harm to challenge your faith, the book certainly gave me (a lapsed Catholic) overwhelming evidence as to the non-existence of a deity.
I still can't get my head around that if people who believe in God say that someone/thing had to create the universe, as it cannot have existed for eternity, then shirley someone/thing had to create God on the same premise?
Even Richard Dawkins admits that he does he cannot prove the non existence of God.
He does however put forward IMO a compelling case to show there is no evidence to support his existence.