dogmatic (adj.)

1680s, of persons, writings, etc., "disposed to make positive assertions without presenting arguments or evidence;" 1706, "pertaining to or of the nature of dogma," from Late Latin dogmaticus, from Greek dogmatikos "pertaining to doctrines," from dogma (genitive dogmatos) "opinion, tenet," literally "that which one thinks is true," from dokein "to seem good, think" (from PIE root *dek- "to take, accept"). Related: Dogmatical (c. 1600).

[T]he dogmatic man insists strenuously upon the correctness of his own opinions, and, being unable to see how others can fail to believe with him, dictatorially presses upon them his opinions as true without argument, while he tends also to blame and overbear those who venture to express dissent. [Century Dictionary]