Joseph Smith escapes from heaven and comes back to earth and has to convince the world that he wasn’t lying in the first place and convert everyone to mormonism after a significant number of the church members leave .

As far as making fun of the LDS belief system and way of life, it seems like the play "The Book of Mormon" has already been there, done that.

As far as making fun of the LDS belief system and way of life, it seems like the play "The Book of Mormon" has already been there, done that.

Is the MC's normal life as in his day to day that of being in heaven? If so then is his banishment form heaven the inciting incident?

I ask because the inciting incident is not clear, what was the specific event that started his story? Lying about god and Jesus or banishment from heaven? If the former then his goal would be forgiveness from god if the later then his goal would be to get back into heaven.

As it stands now there is no clear connection between either inciting incident and his goal of converting all of humanity to mormonism.

Hope this helps.

Comedy

You might want to get rid of the mind control angle.

Heaven is religion
Mind control is science (Science fiction)

Mixing those could be confusing.

Besides fooling the masses without mind control would be a far more interesting and ironic tale.

Mocking as a drama or as comedy?

Mocking as a drama or as comedy?

The main character must be likable in some way, I think that would be a problem for your character.

Joseph Smith is the main character of the film but we're supposed to be mocking him.