The devil has one overwhelming goal and that is to separate as many souls from God as possible. After all - who wants to spend eternity in hell alone? And being the great liar he is he has a whole took box of useful tricks to deceive people and derail any serious attempt to know God.
The first great lie is also rooted in our greatest human weakness - pride. What is the first commandment? "I am the Lord thy God, thou shalt not have strange gods before me." Turn it on its head and you have the Devil's first most effective winning strategy to doom souls to hell. "I am my own God."
Common expressions like: "I will decide what is right and wrong in my life, No one can tell me what to do, I have a right to happiness no matter the cost...." reveal the misconceptions of our day. The fact of the matter is that we are not and never have been God even in our own lives. And because we have a conscience we can make moral decisioins, but it helps - a lot - if we have informed consciences. In other words too often we rely on our imperfect human knowledeg to judge given situations and refuse avenues of learning about God through scripture, commandments, traditions and teachings of church fathers. It seems more independent and spirited (perhaps lazy) to deny or ignore any knowledg of God who knows us best and knows what is best for us. Living as if God had no part ot play in our decisions or putting Him aside when we have to go out into the public forum is neither brave nor intelligent. It takes a great deal more courage and wisdom to pray, to desire the grace of understanding, to be humble before God and to allow Him to influence our lives intimately as well as publicly.
Actually - not being God ourselves is a big relief. Once we let go of the lie we are freed of all its terrible entanglements and we can become what we were made to be - sons and daughters of God. How much better to be a child of God than....the devil's deception.