argumentum ad populum

[I think I am going to start redoing some topics that I have an interest in, rather than attempting to appeal to culters and culteresses.  Who knows, maybe this is what folks want.]

"Why did you smoke pot, Timmy?"

"Well mom, everyone else was doing it, so I thought it was cool"

"If everyone jumped off a roof, would you?"

Most of us can recall a similar conversation from our childhoods. It is usually when parents tell their kids that something is not OK to do, just because everyone else is doing it. To a large extent that makes sense, right? Just because everyone else is doing it, why should you?

Would you jump off a roof because everyone else was? What if the building was on fire, and people partying on the roof figured that jumping off the two-storied building was indeed the best chance of saving yourself?

Then, it is not as clear cut.

Often in argumentation, whether it be on your favorite news program or your debate channel, you would see this invoked: millions of people cannot be wrong.

Millions of Catholics cannot be wrong.
Millions of Muslims cannot be wrong.
Millions of...

As an atheist, I get challenged with this: there exists a God because billions of people around the world, many of them more educated than you, believe in one.

Should I, therefore, believe that God exists, because billions of people do? After all, billions of people believe that the earth revolves around the sun and not the other way around. Let's see if I can draw attention to a subtle point here. I will assert the following:

If a very large number of people believe something, it is probably a good reason for you to believe it too, however, it does not necessarily mean that the belief is true.

So, where does that leave us with popular belief?

"People have a right to believe what they want"

Well, duh! Has anybody tried stopping someone from believing? They can be stopped from saying that they believe, but, actually stopping someone from believing?

People utter that banal truism as if it means something significant. I suspect that people say it because they want it to mean more. That if someone believes something, they have a right to have others accept it as true.

So here's a question. There are things we believe, and not all of us agree on all beliefs. I'll leave this an open discussion with two of my beliefs. I will stipulate that argumentum ad populum, which I discussed above, is a logical fallacy. With that, I'll add two statements.

1. I believe there is no God, despite the fact that billions of people affirm that they believe in one.
2. I believe that anthropogenic global warming is taking place primarily because there is a very broad consensus among climate scientists in the world on the matter. Some 97 percent of them say so, and I am not even one of those scientists.

Do those two statements somewhat contradict each other? Why, or why not?