Is God a human invention?

Today, people are constantly claiming that something is a relative truth. That no absolutes exist. God is dead was Niezche proclamation. How do you handle confrontation between people that deny the existance of God? Where do you even start? First of all, I would point out that God's existance can be found everywhere. From the complexity of the human body, the origin of the world, and the natural world around us- a intelligent creator is a logical conclusion. If they disagree, you could point out the flaws in evolution. Such as, where did the particles that prompted the big bang come from? Deep philosophical questions often will stirr people to question why they believe what they believe. Sarah and Mark are ignoring their own thoughts and bodies by claiming there is no god. Search back into the ancient civilizations and you will find record of a god. Perhaps not he god of Christianity, but at least some reference to a higher being. Without the existance of God and therefore salvation the human life becomes very short. You are born and then you die. It is a scary thought. There is no explanation for the hard times of your life or the good times, you are left in a state of apathy and fear.
        However, I will not disagree that society creates its own gods. Not the true God, but certainly they invent their own personal god. Either they themselves are the god (as with cosmic humanism) or the state/government becomes their god. This, in itself, proves humanity's need for a higher truth and law. Humanity needs some kind of salvation.
        In response to Mark's comment that man should evolve past our need of God, Mark obviously disbelief in God negates man's need for him. However, Mark misunderstands the purpose of God, He is our salvation and we will always need Him. Thus, I would describe the nature of God and His love and grace to Mark, allowing him to receive an objective view of Christ. Obviously, to believe in God requires an amount of faith but importantly God is a logical explanation of our world. It is not blind faith, but faith prompted by historical evidence and personal experience. The world is complex and thus demands a complex God.
       Proving the existance of God to an atheist will require patience and prayer. Although my belief in God is one hundred percent strong, an atheist has no knowledge of who God is or what He does.