Is disbelievement a valid word? if not, what word could I use instead?

It is being used as a noun in this context: The disbelievement of the people...

I couldn't find disbelievement -- so I suggest you not use it.

The disbelief of the people . . . would be much better.

disbelievement is not a word, but you could make it one, like in the frindle! haha

Believe this:

the correct word is:
d-i-s-b-e-l-i-e-f

http://www.merriam-webster.com/dictionary/disbelief

Yes, "disbelievement" is not considered a standard word in the English language. The correct term to use instead would be "disbelief." In the context you provided, you can say, "The disbelief of the people" to convey the intended meaning.

To determine whether a word exists or not, you can refer to a reliable dictionary. Online dictionaries such as Merriam-Webster or Oxford English Dictionary can provide you with accurate information regarding the existence and usage of words. Additionally, you can utilize search engines to check the frequency and common usage of a word in various contexts.