"For yourselves, brethren, know our entrance in unto you, that it was not in vain:
But even after that we had suffered before, and were shamefully entreated, as ye know, at Philippi, we were bold in our God to speak unto you the gospel of God with much contention.
For our exhortation was not of deceit, nor of uncleanness, nor in guile:
But as we were allowed of God to be put in trust with the gospel, even so we speak; not as pleasing men, but God, which trieth our hearts."
1 Thessalonians 2:1-4
These verses are from a letter Paul wrote during his mission to the Thessalonians. It's interesting that it mentions contention, since we know that "he that hath the spirit of contention is not of me, but is of the devil," (3 Nephi 11:29) after all. Perhaps though, contention is something that we are going to encounter as we share the gospel. Not because the spirit works through contention, but because no matter how well we work in going out to do good, we will meet with resistance. Even Christ, the perfect man, found opposition, doubt, and offense in people's reactions to the gospel, even though none of that was inherent in his message.
So, if we're going to run into that kind of resistance doing missionary work, then why do it? I hear this question sometimes, and I think it is an easy thing to wonder. Why spend time preaching when there is so much good to be done just helping? I think we forget though, that the gospel does help people. It isn't really the story of Joseph Smith or anyone in the Book of Mormon. It isn't the rules about drinking or chastity. It isn't even modern day prophets or the atonement, although of course all of those things are true, and remarkable, and life-changing. The part that really helps people though is the everyday part... the prayer, and the scripture reading... any scripture, any story. It's the relationship with God that everyone can have... the realization that God is there to talk to, all the time. The listening to him, the learning from him. The recognition of his hand in our lives. Which leads to trust, which leads to faith, which leads to joy. Learning how to talk to and listen to God is more valuable long term than being lifted out of poverty or illness, or even having our physical sight miraculously restored. The spiritual sight will help us so much more. ... And totally not that we shouldn't be working to help each other in both ways, of course. I'm just saying that missionary work is valuable, because having an individual relationship with God makes us spiritually self-sufficient in a way. We need a lot of practice and support, but we learn to go to The Lord with questions, and how to listen to his answers. Missionaries really are there to help... not to deceive or trick, but to share the gospel that God has entrusted us with. It isn't always going to please men, but it pleases God... And that's what matters.
In this same chapter, verse 12, Paul says one of their goals in preaching I s to help people "walk worthy of God." That's a process. Truthfully, none of us really are walking worthy until far down the path. We don't deserve even to scrub God's floors in Heaven... but God trusts us with the Gospel anyway... helping us learn and grow and change and eventually come and hang out with him full time. We are fortunate that he loves us enough to still let us try, let us learn, even knowing ahead of time that we are going to fail more often than we succeed. He doesn't worry that we are ruining things. He can fix it all. He just loves us so much, he wants us to keep trying until we get back to him. Like a video game with unlimited lives. And the only way we screw up infinite chances is by giving up and walking away. :) Our entrance into missionary work, or whatever other calling we accept from the Lord, is never in vain. We just need to have enough heart to keep trying, and learning, and staying on the path. If we can, we'll all eventually get there. :)