The argument for the existence of God is an existential one: it has to do with the state of our being.  Of course if we have it all together, one can use rational arguments to refute the existence of God, but if we are up against it, if we are plagued by our own shortcomings, if sin has a hold on us which we are incapable of budging, then the need for God is real.  In John's gospel chapter eight Jesus states that he that committeth sin is a slave to sin and that only the Truth can make you free.  So unless you are in bondage to sin, unclean spirits, fear, anger, in short, the deeds of the flesh, you can sit smugly in your reason and ability to dispute, but if you are up against it, only Jesus, the way, the truth, and the life can make you free.  We are saved by grace through faith and faith comes by hearing the word of God.  It was only when I began to study the word of God and invited Jesus into my life that Jesus became real, that I received a hunger and thirst for righteousness, and the word of God became the most important book I ever read.  Jesus Christ came into this world for sinners not the self righteous and only by the gift of repentance is salvation obtainable.  I could tell you that the pain and suffering of this world is due to the fall of Adam and Eve.  I could tell you that the devil is the prince of this world and has great power to deceive, but knowing that is not enough.  One has to experience God personally and be washed in the blood of the Lamb.  One has to overcome tribulation and persecution.  One has to overcome the cares of this world, the deceitfulness of riches and the lust of other things for the word to bear fruit and unless one puts the word of God into practice, he is building his house on sand.  That house will fall when the storms of life challenge it, but if you build your house on a rock, you can withstand every onslaught of the evil one.