Yes, HERETICS is a Scrabble word!

Letter values in Scrabble US: H 4, E 1, R 1, E 1, T 1, I 1, C 3, S 1.

Is it a valid word?

HERETICS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a person who holds religious beliefs in conflict with the dogma of the Roman Catholic Church
a person who holds unorthodox opinions in any field (not merely religion)

Also: religious outcast.