Christians are followers of Christ as the word itself indicates. There is no need for further qualification. One who is a follower of Christ needs only His word as recorded in the Bible, along with the inspired writers chosen by Him, to know what is required of Him (II Tim. 3:16-17).
New American Standard Bible (NASB)
14 As a result, we are no longer to be children, tossed here and there by waves and carried about by every wind of doctrine, by the trickery of men, by craftiness in deceitful scheming; 15 but speaking the truth in love, we are to grow up in all aspects into Him who is the head, even Christ, 16 from whom the whole body, being fitted and held together by what every joint supplies, according to the proper working of each individual part, causes the growth of the body for the building up of itself in love.