Is to abstain
Behold, the only [true] religion in the sight of God is [man's] self-surrender unto Him; and those who were
vouchsafed revelation aforetime took, out of mutual jealousy, to divergent views [on this point] only after knowledge [thereof] had come unto them. But as for him who denies the truth of God's messages - behold, God is swift in reckoning!
~ al-Imran 3:19
And be not like those who have drawn apart from one another and have taken to conflicting views after all evidence of the truth has come unto them: for these it is for whom tremendous suffering is in store
~ al-Imran 3:105
VERILY, as for those who have broken the unity of their faith and have become sects - thou hast nothing to do with them. Behold, their case rests with God: and in time He will make them understand what they were doing.
~ al-An`am 6:159
[For, thou art the bearer of a divine writ] such as We have bestowed from on high upon those who afterwards] broke it up into parts,- al-Hijr 15:90 [or] among those who have broken the unity of their faith and have become sects, each group delighting in but what they themselves hold [by way of tenets].
~ ar-Rum 30:32
In matters of faith, He has ordained for you that which He had enjoined upon Noah - and into which We gave thee [O Muhammad] insight through revelation as well as that which We had enjoined upon Abraham, and Moses, and Jesus: Steadfastly uphold the [true] faith, and do not break up your unity therein. [And even though] that [unity of faith] to which thou callest them appears oppressive to those who are wont to ascribe to other beings or forces a share in His divinity, God draws unto Himself everyone who is willing, and guides unto Himself everyone who turns unto Him.
~ ash_Shura 42:13
And [as for the followers of earlier revelation,] they broke up their unity, out of mutual jealousy, only after they had come to know [the truth]. And had it not been for a decree that had already gone forth from thy Sustainer, [postponing all decision] until a term set [by Him], all would indeed have been decided between them [from the outset]. As it is, behold, they who have inherited their divine writ from those who preceded them are [now] in grave doubt, amounting to suspicion, about what it portends.
~ ash-Shura 42:14