Can they (Muslims) who rely on a clear proof (the Quran) from their Lord, and whom a witness [Prophet Muhammad through Jibrael (Gabriel)] from Him follows it (can they be equal with the disbelievers); and before it, came the Book of Musa (Moses), a guidance and a mercy, they believe therein, but those of the sects that reject it (the Quran), the Fire will be their promised meeting-place. So be not in doubt about it (i.e. those who denied Prophet Muhammad and also denied all that which he brought from Allah, surely, they will enter Hell). Verily, it is the truth from your Lord, but most of the mankind believe not.
Meaning:-
Sects: a group of people with somewhat different religious beliefs (typically regarded as heretical) from those of a larger group to which they belong.