Hitler was not in a position of control over the German army in a way that would allow him to remove people out from the ranks. He couldn't legally get rid of the subversive traitors that were sabotaging from within the army because that was not part of his political rights. This is the whole reason he made the SS, so there would be an army who he does have control of, and he can pick only the best people and exclude the bad people. The evil subversive rat traitors in the high levels of the German army were the entire reason that they lost. They would purposefully do the exact opposite of what Hitler told them, to purposefully make the biggest problems they could.
That documentary is full of lies, it is propaganda meant to make people think that Hitler was christian, or he was jewish, and all kinds of other nonsense. Hitler did everything in his power to erase christianity and reinstate the true universal order of nature.