1 John 3:11-12, 23

For this is the message which you [believers] have heard from the beginning [of your relationship with Christ], that we should [unselfishly] love and seek the best for one another; and not be like Cain, who was of the evil one and murdered his brother [Abel]. And why did he murder him? Because Cain’s deeds were evil, and his brother’s were righteous.

This is His commandment, that we believe [with personal faith and confident trust] in the name of His Son Jesus Christ, and [that we unselfishly] love and seek the best for one another, just as He commanded us.