Hebrews 2:1; Hebrews 9:26; Hebrews 11:6

Hebrews 2:1

1 We must pay the most careful attention, therefore, to what we have heard, so that we do not drift away.

Hebrews 9:26

26 Otherwise Christ would have had to suffer many times since the creation of the world. But he has appeared once for all at the culmination of the ages to do away with sin by the sacrifice of himself.

Hebrews 11:6

6 And without faith it is impossible to please God, because anyone who comes to him must believe that he exists and that he rewards those who earnestly seek him.