"Pick a side, breh!"
Life, dear brothers and sisters, is one big test. Heavenly Father wants us to prove to him that we can make the right choices while in our mortal bodies (hint: choose the right, y'all!)
Here's how it works: Heavenly Father gave us free agency on earth in part so we could experience the joy of being wrong from time to time in order to learn how to be right all the time. God wants us to be perfect, just like he is, but that requires a fierce trial of our faith (God's very into testing our fidelity, BTW). Part of that trial involves an invisible host tempting us and trying to deceive us. We have to figure out when those devils are speaking to us. See, God wants us to make mistakes so we can learn, BUT he also hates mistakes because they're either totally below him or just down right evil (he refers to many human shortcomings as sin) and won't let anyone around him who makes them. So what he did was make a law that it's OK to kill a perfect someone (in our case Jesus) to somehow make up for all the bad decisions we're responsible for. So we're responsible for learning to being better but mostly just responsible for learning about Jesus and being grateful to God for killing him sacrificially to himself for us. In other words, he needs to know that we are smart enough to accept the Atonement for all the mistakes we've made, and we do that by being baptized and then joyfully sitting in church for three hours on Sunday and various other long hours throughout the week.
Sign us up for team Most High God!
It's not too hard to see why someone might not get on board with this plan right away - mostly because that whole vicarious sacrificial atonement part makes absolutely no sense. Satan (our spirit brother formerly known by his Latin moniker, Lucifer) was one of those spirits who didn't like God's plan, and - even though God's plan clearly called for a bunch of rebellious spirits to trip up the non-rebellious as best they could - somehow he was too fucking stupid to realize that by not accepting God's plan he would totally become the sorry ass evil spirit to plague the children of men. So this totally fucking stupid Satan made his own ludicrous plan, in which he would somehow force everyone to behave themselves by somehow denying them any kind of autonomous control of their thoughts and actions (we don't have any more specific details than that) so we'd never make mistakes and all be perfect so God wouldn't have a problem with us being around him after we die. The problem is no one can learn and be happy with someone else making all their decisions for him or her.
Satan's sad evil drone clones.
Now we come back to where we started, according to Mormon thought, to be happy we must make our own decisions. If you don't believe it, just look how unhappy people are under dictators! So make your own choices, learn, and learn to be happy. Just make doubly goddamn sure you believe killing Jesus magically liberates you of your every sin and weakness, get baptized, become a member of the One True Church, pay 10% of your gross income to the Church, attend your weekly Sunday meetings, eat enchanted bread and pretend it's Jesus meat, drink enchanted water and pretend it's Jesus blood, think how the Brethren tell you to think, find another Mormon of the opposite sex who does all of the above, marry that person of the opposite sex in the House of the Lord, have sex, make babies, and teach them these marvelous truths... because otherwise God's going to be pissed and he won't let you hang out with him ever again!
What's that? You don't like how this is panning out? It doesn't sound meaningful enough? It sounds downright arbitrary? Really? Well what does the secular world offer you here? Is it any better? What according to the secular thought is life all about? I'll tell you: NOT MUCH!
Lame! You stole this from Jesus!
Waaa! You're so persecuted!
Secularist think you can make up your own meaning of life! They actually think you have the ability to come up with your own reasons for living! It's absurd! Find your niche and thrive in it, they say. Where would such absolute autonomy over your own life come from? Why not just accept and conform your life to Mormon meaning of life? It's easier and guaranteed to make you a god.