First, just about everything you have heard or continue to hear about Hitler or WW II in general is complete bullshit. Deal with it. Next, not long after WW I, the allies actually sent troops into Russia to help fight the Bolsheviks. So it makes no sense to have supported them in WW II. Also, Russia was mainly an oriental society. This was probably a leftover of them having been ruled by the Mongol Golden Horde for centuries. Germany was at least a more civilized, advanced and "Western" country. So not backing Hitler makes no sense.
Maybe the reason the allies didn't back Hitler was because after WW I, Germany had around 65 billion in GOLD stolen from it as reparations for WW I. Which was a war that Germany just got sucked into like everybody else. But when Hitler came to power, he put a stop to those reparations payments. (Germany made their final WW I reparations payment in 2010)
Maybe this next reason is the right one. Before Hitler came to power, unemployment was rampant in Germany. Germans also literally needed a wheelbarrow full of money to buy a loaf of bread with. Hitler fixed all that. Maybe the reason the allies didn't back Hitler was because he PROVED that National Socialism was superior to what our democratic capitalist system was. (Or still is)
Another thing is that Germany invaded Poland on September 1, 1939. Mist likely because of ethnic Germans living in Poland were being murdered. But it didn't take the allies long to declare war on Germany when they did so. Though when Russia did the same thing 2 or 3 weeks later, war wasn't declared on them. Neither was it when Russia invaded Finland on November 30, 1939. Then on June 22, 1941, Germany invaded Russia. Most likely because they found out that the Russians were getting ready to invade them. One historian I read about claimed that Germany beat Russia to the punch by only one day! So what did the U.S. do when Germany invaded Russia? They started sending the Russians supplies and munitions! Even though we weren't at war with Germany yet.
I will give you what I think are the two main reasons why the Allies didn't back Hitler. First, to most Christians, a good way to prove the power of their imaginary god is to back the jewish people. And before war put an end to the program, Germany DARED to deport 60 to 70% of its jews to Palestine under The Haavara Agreement.
The other reason comes in the form of two pictures. The first is an image from the first "talkie" that the jew Charlie Chaplin did. There was no doubt other jewish BS propaganda being spread around back then. (And still is) The second picture with quote is of a jew who was the head of the Russian NKVD. This one jew alone is said to have orchestrated the deaths of at least 10 million people!
Our WW II servicemen have been called "the greatest generation." Yeah. The Greatest Generation of SUCKERS! And you're all still being suckered.