If you ask an atheist why they believe there's no God, you may get a number of responses. From weak and lazy arguments like "there's no evidence" to arguments that would have been reasonable if we hadn't answered them hundreds of times over throughout the centuries, like the "problem" of evil, there are a number of reasons atheists give for disbelieving in God.
By far one of the most common arguments, however, is the subjective desire for there to not be, at the very least, the Christian God. Atheists love to object to God based on things they don't like about Him. His wrath against sinners in the Old Testament, His condemnation of their favorite sins, the very existence of Hell, these are just a few common examples. Based on their ideas of what they would want God to be, they argue that God cannot, therefore, exist.
But I want you to think, for a moment, about how silly this argument is. Because we are not gods ourselves, we cannot change reality based on our desires. We cannot say "let there be light", and thus create light. Nor can we call down fire from Heaven to consume that which we find objectionable. The fact is, this fallen world is filled with things we don't like. Not many of us like cancer, yet "cancer is horrible, it causes so much pain and suffering" is a silly reason to suggest that cancer therefore does not exist.
Furthermore, people disagree with us in a number of different ways. I like to use the example of Alex O'Connor, a.k.a. Cosmic Skeptic, and Matt Dillahunty of the Atheist Experience as a prime example. These two men, both atheists, have very different views on the morality of veganism. They once met to discuss the topic, but it's clear that they'll never actually agree. Now, can either of them argue that because they don't like each other's views, therefore they were debating an empty chair the whole time? The obvious answer is no.
And that's just two atheists. But human disagreements vary more wildly than the chaos of atheism. There are people who believe the exact same things these same atheists argue God cannot exist because He believes them. "God disagrees with abortion". I disagree with abortion. Am I an imaginary sky fairy? There are people out there right now who are so detestable, they are willing to kill you for disagreeing with their religion. This cannot be used to say the people do not exist, so how can anything you disagree with be used to say God, without whom none of us could exist, does not exist?
The greatest absurdity of this is the very expectation that God would even necessarily agree with us. For one thing, while He is omniscient, we are not. Do you truly imagine your limited knowledge and experience could be pitted against God? You, whose moral views have changed multiple times over the course of your insignificantly short life, should be allowed to stand judgement over the eternal, unchanging God? Being by your own admission imperfect, you believe you get to decide whether God falls short of your standard? Is this not the absolute height of arrogance?
Even vegans, like the aforementioned Alex O'Connor, must assume a degree of authority over the natural world. The farms that feed us must be maintained at the cost of animal life. Their homes must be destroyed to create the space to grow our crops. Crops they must be prevented from eating, often violently. Unless he wants us to become animals and just return to survival of the fittest (at which point what stops us from killing them for that same goal anyway?), he must accept that humans are greater than animals; a concession that all vegans must make. And yet, the distance between man and beast is significantly smaller than the distance between man and God.
God has both right and reason to disagree with us. Therefore, it is illogical to suggest He doesn't exist because He uses those reasons to exercise those rights. In fact, it stems from our own desire to sit on His throne. It takes the height of arrogance to assume your preferences are so important that they can be substituted for an objective argument. Thus, atheists show their cards a little too brazenly every time they do so.
But even the atheist desire to be God can be forgiven by God, all at the expense of the one man who gave enough evidence for God to warrant execution by others who wanted to be God. Jesus, being God in flesh, never sinned in any way, shape, or form. He is the height of perfection, yet He died a sinner's death, receiving in Himself the full penalty for sin. For that reason, thousands of ex-atheists have found His grace, receiving the free gift of eternal life, being forgiven for every time they believed they could usurp God's authority. If you confess Jesus as Lord, and believe He rose from the dead, you can too.