Atheism isn't an outright rejection of god/gods/the supernatural/etc. Though many atheists do this (called "strong" atheists), I do not. I wholeheartedly support the possibility of these things. Possibilities, though, are not beliefs. If I were to examine every possibility for something before being able to doubt it and not adopt it, I'd be occupied all day with meaningless searches for unicorns, fairies, and flying spagetti monsters. Atheism is simply a lack of belief, and belief in gods is something I completely lack.
I've put forth much effort, I'm not convinced of anything. I'm not being arrogant here, I simply haven't. What convinced those who do believe?
first i would like to lift a quote for Ravi Zacharias' website:
Isnt it self-centered and immoral of God to condemn those who do not believe in Him on the grounds that there is just not sufficient proof offered for His existence? Now pause for a moment and think of the way that charge has been phrased. There are several assumptions here. The first is obvious--the invocation of a moral law
that God is morally bound to give us sufficient evidence. But a moral universe is a luxury an atheist cannot afford. There is, however, a not so obvious factor here.
Atheistic philosopher Bertrand Russell was once asked what he would say if he found himself standing before God after death. Russell said, I will simply say to him, You have not given me sufficient reason to believe in you. But to Russell I would say that evidence can be sufficient without being overbearing.
The fact is that God has given us one of the greatest privileges as human beingsOur free will. The privilege of self determination. That freedom is a necessary moral component of love. One cannot be credited with love, unless it is also the prerogative of that person not to love. For us to be truly free, there entails the possibility of us rejecting the love God offered to us.
May I propose to you that the atheist who demands a compelling evidence such that it is not possible to disbelieve, may in fact be demanding that which diminishes love at the same time. Ironically, it was Bertrand Russell who lived with numerous infidelities and betrayals. One has to wonder how a moral basis is invoked for the rejection of Gods love while the breaking of another love does not appear immoral. Quite duplicitous, I would think.
So rich is the body of evidence that God Himself reminds us that the problem is not the absence of evidence, rather the suppression of it. If Russell and others would apply the same tests for truth to the claims of Christ that they apply to other disciplines, they would find the evidence compelling. In short, the problem is that of the heart and not of the mind. One who says there is not enough evidence tells us more about himself than about this universe.
Let me also say this, nobody will end up in an eternity without God apart from their own choice to be such. In other words, even heaven would be hell for somebody who wanted to be autonomous in this world. They have made their choice to live in this world apart from God and in doing so, they make the choice to live in the next world apart from Him also. Maybe that is why Dostoevsky defined hell as the inability to love.
Then i'll tell you a few things that convinced me of God's existence and specifically the God of the Bible.
1) The order of Creation. If you can look at all the wonderful things around us and NOT think a higher power put it all together, you must be crazy (imho of course). I mean there are 6 billion people, 70% of the world is covered in oceans, there are billions of insects, millions of animals, millions of different plant species. We are rotating on a ball in the middle of space. A little farther out and we'd freeze. A little closer and we'd burn. The intricacies of the human body. The fact that from one cell we get toenails, hair, mucus, skin, bone, cartilage, eyes, ears, lungs, etc is amazing to me! So Creation is #1. When i try to share my amazement at Creation, i've heard an atheist just reference the # of naturally aborted fetuses. How sad. Their eyes are totally blind to the beauty of creation when they choose just to observe a negative part that is a result of the Fall.
2)the textual evidence for Scripture. There is no other literary document in HISTORY that has more evidence of it's authenticity than Scripture. There is not even a close 2nd place. There are literally over 10,000 manuscripts relating to the Bible. We have NT manuscripts from the early 2nd century (~A.D. 130). This fact helps a lot of people that have "trouble with faith". People accept the authenticity of very early works like Homer's Odyssey and some of Plato's works and there might be 1 surviving manuscript. So #2 would be textual evidence. Search as much as you want but you will not find any piece of literature with as much support as the Bible.
3) Christianity answers the existential questions i have and makes sense as a whole more than any other book i've read. Who created me? God. What is my purpose in life? to glorify God. What happens after i die? heaven or hell depending on my relationship with Christ. Why does evil continue to happen? God allows people the choice of loving him or rebelling against him.
When i read about other religions, they just weren't ultimately satisfying, meaning they sounded like they were written by someone who's pretty smart and graduated from an Ivy League school, but not God. For example, when i read through the Satanic Bible one of the main messages was basically that "he who dies with the most material things, wins" b/c this is all there is. I know fundamentally in my core that this is just foolishness. I could go to any billionaire's grave, dig them up and kick their bones. Or i could put them in a grinder and grind them to dust. They can do nothing. They have no feeling, no enjoyment. If this is all there is, well their lives were pretty meaningless. When i look at how much attention to detail was given to all of Creation I know in my heart that this is not just all there is. This life on earth is important, SUPREMELY important. But Satan, sin and death have tainted it and until Jesus judges and renews the new heaven and new earth, we are bound here.
Again, you can look at many other religions, like taoism, buddhism, hinduism, new age stuff and you will find a similar theme: the downplay of humans and human living. For buddhists it's the eightfold path to Nirvana. For hindus it's constant reincarnation until perfection and then unity with the Source. For taoists it's more of an evolution past life on earth, just as the dead evolve past the realm of the dead.
All of these religions make it seem like you have forever to leave your bad ways behind and become good. If you don't do it this life, you will suffer a little, but then you have a chance to do it next life. Or some people will make it "there" in 10 years, others it will take 10,000 years. But the timing doesn't matter as long as you are going in the right direction.
This is a common lie of Satan through many of the world religions today. He wants us to believe that we have as much time as we need so that when we die, we are totally unprepared for judgement. The Bible says that man is appointed to live once and die once and then be judged. This fits in with the importance of life and the order of creation. So point #3 is that it just makes sense. It is more thorough and answers more questions fully than any other religion i've come across.
But obviously the #1 reason i believe is b/c Jesus drew me to Himself. I could not believe on my own for even Faith is a gift from above.
My fingers hurt, so i'm gonna stop typing for a bit, but i wanted to give you an answer for why i believe. I don't want you atheists thinking us Christians haven't thought things through. If only i was as smart as Ravi Zacharias or William Lane Craig i could beat you guys in these debates.

But i'm not and anyways it's ultimately the Holy Spirit who will bring you to God, but i like to give it a go every once in a while anyways.
Blessings.