Let's take a look at Hitler.
When Hitler came to power, he outlawed atheist and freethinkers groups, including the German Freethinkers League which, as I understand, had half a million members. Why would he disband the group if he was himself an atheist?
The SS had a "Loyalty Oath" sort of like the Pledge of Allegiance. It went like this:
"What is your oath ?" - "I vow to you, Adolf Hitler, as Führer and chancellor of the German Reich loyalty and bravery. I vow to you and to the leaders that you set for me, absolute allegiance until death. So help me God !"
"So you believe in a God ?" - "Yes, I believe in a Lord God."
"What do you think about a man who does not believe in a God ?" - "I think he is arrogant, megalomaniacal and stupid; he is not eligible for us."
The Nazis really didn't care for non-believers, did they?
Next: the slogan on the belt buckles and other bits of armour of the German army. Now, the slogan existed prior to the Nazis but the Nazis did nothing to change it. The slogan was
Gott Mit Uns
which, if your German is good, you'll know means "God With Us."
Allow me to quote some bits from Mein Kampf:
Hence today I believe that I am acting in accordance with the will of the Almighty Creator: by defending myself against the Jew, I am fighting for the work of the Lord.
On April 12, 1922, Hitler gave a speech, wherein he said
My feelings as a Christian points me to my Lord and Savior as a fighter. It points me to the man who once in loneliness, surrounded by a few followers, recognized these Jews for what they were and summoned men to fight against them and who, God's truth! was greatest not as a sufferer but as a fighter. In boundless love as a Christian and as a man I read through the passage which tells us how the Lord at last rose in His might and seized the scourge to drive out of the Temple the brood of vipers and adders. How terrific was His fight for the world against the Jewish poison. To-day, after two thousand years, with deepest emotion I recognize more profoundly than ever before the fact that it was for this that He had to shed His blood upon the Cross. As a Christian I have no duty to allow myself to be cheated, but I have the duty to be a fighter for truth and justice... And if there is anything which could demonstrate that we are acting rightly it is the distress that daily grows. For as a Christian I have also a duty to my own people.
I could go on. Do you have evidence that Hitler was lying the whole time?