Spiritual development is not easy. It takes both time and effort. For that reason, as well as others, many people decide not to bother. It causes many to decide that the spiritual world, God and angels don't exist. They have no proof of that, but they accept this belief because it makes things easier for them. They don't have to worry about how to worship God if they don't believe in Him. They don't have to wonder what part they play in God's plan id they don't believe there is one. It's all very convenient, but that doesn't make it true. 
    A hypnotist can make you believe that the moon doesn't exist. If you look up at the full moon, you will not see it. You have been convinced that it isn't there so you filter it out. But is it really gone? No, it isn't. Others can still see it. Others you will probably consider insane, or at least confused, because obviously there is no moon there! Now if the hypnotist releases you for what he previously told you, you will now see the moon again. 
    So, contrary to what some self-help gurus teach, believing in something doesn't necessarily make it true, neither does disbelief make it false. Believing that you can accomplish something does make it possible, but not necessarily true. On the other hand, lack of belief pretty much guarantees that you won't accomplish it because you wont even try. 
    So just because spiritual development has to be worked at, doesn't mean you can make the obligation to do so go away by pretending that God doesn't exist.