this is hard to answer and to be short about it. but God is a  holy God that can not the presence of sin. man is born with sin and needs to be cleaned of it to have a relationship with God. the only way to be cleansed of sin is blood. (the Passover story) since man could not pay his own sin debt He sent His Son to die a brutal and terrible death on the Cross. (psalm 22) from there faith takes over where a person needs to believe in Jesus for the payment of his debt. if a person does they are put in a right relationship with God. (john 3:16).as you can see (by the other answers) faith is a hard thing to have. hope this helps.