There are several causes of people not believing God exists. 1. Some think there are contradictions in science and the Bible. They are not aware that what they think is science that contradicts the Bible is not really science, but more opinions. There are things which some think the Bible teaches which contradicts science.
2. Division in the religious world is another cause of unbelief. The atheist, Robert Owen, said in his debate in 1829 with Alexander Campbell that one reason he was an atheist was because of conflicting doctrines of religion. Jesus prayed that all believers in him would be one "that the world may believe that thou hast sent me" (John 17:20-21).
3. Those who claim to be followers of God, but live corrupt lives, cause unbelief.
4. Perhaps some are not willing to be under God's authority. They do not want to be suppressed in their lifestyles. They get "relief" by not believing in God.
Those who do not believe God exists are called atheists. Even though they do not believe God exists, they do believe some things which are harder to believe than to believe God exists. In fact, one cannot be an atheist without believing a number of things which are harder to believe than believing God exists.
1. To know that God does not exist one would have to know everything, for if there were just one thing he did not know, that might be that God exists. So, to be an atheist one has to resort to faith and believe God does not exist. He leans on faith while he chides others for leaning on faith.
If an atheist is right, he can never know he is right because he cannot know he is right until he knows everything. Since he will never know everything while he is living, he will not know he is right in believing there is no God as long as he lives, and certainly will not know he is right after he dies, for if he is right he will not exist any longer!
2. To be an atheist, one also has to believe that matter has either always been here, or that it was produced by nothing from nothing! He must believe that matter has always been here or that it came into being without intelligence being involved.
3. One cannot be an atheist without believing that life came from that which was not alive.
4. One must believe that his mind with which he does his believing came from that which was mindless and therefore thoughtless.
One should be kept from becoming an atheist by just thinking about all the things he would have to believe to be an atheist.
We know things in different senses. We do not know God exists in the sense that we have seen him, but we know he exists on the basis of evidence for which we cannot give account if he does not exist. Being confident about God's existence should constrain us to love him, and be in awe of him, and to serve him with all our hearts.
The fact that we have the idea or concept of the Almighty God in our minds is good evidence for our knowing he exists. Where did we get that concept? Someone will say we got it from our parents or others. But, where did they get it? Go back as far as you will, and reason demands that either that concept was conceived in someone's mind or it was revealed by God.
How did someone conceive the concept of God if there is no God? Did someone think up something that did not exist? Reason and common sense say, no. If God does not exist, no one got the concept of his existence by seeing him, by feeling him, by hearing him, by tasting him or by smelling him. But, these senses are the means by which we get our concepts. It is reasonable to conclude that God made himself known to man just as the Bible says.
The fact that we can talk is evidence for our knowing that God exists. Scientists say that a baby that does not hear someone talk cannot learn to talk. How did the first person learn to talk? It is reasonable to say God either made Adam and Eve so they could talk, or they learned to talk by hearing their Maker talk! I believe God made them so they could talk and with vocabularies from their very beginning!