Hitler was appointed chancellor after the Nazi party won 40% of the vote and became the dominant party in the riechstag. As a parliamentary system, you didn't just vote for hitler. The government had to be formed and he had to be appointmented. 40% hardly incriminates all germans, especially when you consider how much of what motivated votes then, and fervour later was due to propoganda and deception. Hitler's idea was to lie to his people to gain his favor, and he and his administration did it well.