So then faith cometh by hearing, and hearing by the word of God.
— Romans 10:17 (KJV)
All of us make sinful choices against our own conscience. Cain served God on his own terms, increased his sins with murder, lied to God and tried to justify his sins, and departed from God without remorse. Cain killed his brother because he hated but Christ - the only Savior who can save us from our sins - was killed for His brethren because He loved. Cain had a choice to repent but he chose to multiply his sins. The choice is there for us too. What will we choose?