When God made you, He gave you a built-in "firewall" to protect you from making destructive decisions. Without this firewall, man is prone to destroy his life and the lives of others by choices that go against God's will. This firewall is known as the human conscience.
Your conscience is a gift from your Creator. He gave it to you because He loves you and He wants to help you do the right things. He wants you to feel guilty about your sin, and to feel good about His love and forgiveness. When there is no guilt over sin, there is no awareness of the danger you are facing and the harm you are causing.