Why are we doing this?

Mormons believe God is a very fair judge. The fairest. No detail escapes his infinite wisdom.

"The Lord’s way of final judgment will be to apply his perfect knowledge of the law a person has received and to judge on the basis of that person’s circumstances, motives, and actions throughout his or her entire life." Book of Mormon Teacher Resource Manual, 2004, 304.

So why bother with the whole missionary work thing? Why do we need to convert the entire world to Mormonism if God doesn't need Mormon law to judge everyone perfectly? All he needs is "his perfect knowledge of the law a person has received" and he has that! Why force new laws on people if it makes no difference to how they are judged? Why not just encourage everyone to be kind and let them sort life out they way they see best? God will still judge them relative to their cultural and psychological circumstances. It's not like we're doing God a favor by telling people God is Mormonly rigid in making judgements. Don't we believe that God knows the desires of our hearts and will judge us according to those desires?

"And it is requisite with the justice of God that men should be judged according to their works; and if their works were good in this life, and the desires of their hearts were good, that they should also, at the last day, be restored unto that which is good." (Alma 41:3)