The mark of a true disciple of the Lord Jesus Christ is faith and obedience. But Jesus was not calling men merely to believe in Him, but to follow Him with their whole lives. The disciple listens to the word of Christ, believes it with all of his heart, and keeps it day in and day out; he turns away from his sin, remains lowly in humility, and denies himself. This is evidence that he loves Christ.
“If anyone desires to come after Me, let him deny himself, and take up his cross daily, and follow Me” (Luke 9:23).
But let us not forget that a true disciple is known by love, love for God, love for others. Jesus made love the central sign of true discipleship, and His followers are to manifest God's characteristics toward His children. In love this means being forgiving, being merciful, and doing good deeds. A disciple seeks peace, helps those in need, and is kind to those who do not love him.
Jesus clearly said, “By this all will know that you are My disciples, if you have love for one another” (John 13:35).