Cam Griffin had 19 points for Denver (1-1).
Saint Mary's led 34-26 at the half as Waldow scored 16.
Denver was within 10 on Jake Pemberton's 3 at 9:28 but the Gaels got back-to-back baskets by Carter and then pushed the lead to 17 on Bright's 3 and a Waldow layup with 6:36 left.
The Pioneers got it back to 10 late but Naar and Waldow responded to start a game-ending 8-2 run.
With Waldo grabbing seven rebounds, the Gaels had a 31-21 advantage on the boards.