The devil is the father of lies

Notice that Satan lied to Eve when he said to her, “Ye shall be as gods”, or simply put, “You will be god” (Gen. 3:5). The devil knows there is only one true God, and understood that Eve would not be god, but he wanted Eve to trust in herself as god, and be independent from the One True Living God and not trust in Him. 

Satan still uses this lie today. What does Satan want? He does not want people to come into a relationship with God through Christ and go to heaven, but to remain in their sin and rebellion against God, and go to hell; all false religions and cults which includes atheism accommodate the devil's desire. Atheists believe the lie that they can be independent from God, just like Eve believed in the Garden of Eden. The many people who claim to be atheists want to set their own moral standard and say what is right and wrong because they have pleasure in unrighteousness. They make themselves believe they are not accountable to the true living God by deceiving themselves to believe the lie that there is no God. The reason is because they want set their own moral standard that allows them to have pleasure in sin, thus to make them feel comfortable in their practice.