So often when I am suffering I see people and hear people sharing "doctrines" that are supposed to help, but actually make things worse. They are false doctrines that we use to soothe our own souls (not really those who are suffering), to make sense of someone else having to suffer, and to relieve us of responsibility to do something about it.
"Everything happens for a reason." Every time I hear this I think about child abuse. Yes--that abuse happened for a reason. The reason was there are wicked people in the world. It is not true that everything is set up and controlled by God, or else God is a monster and there is no agency. But there is agency and humans are the monsters. And some things just happen, not controlled nor set up by God.
"You won't be tested above that which you can bear." Yes, you will. Else why would you need Jesus? The point is not that we can do it ourselves, but that we can't. This, I think, is a corruption of this scripture, Alma 13:28-29: "But that ye would humble yourselves before the Lord, and call on his holy name, and watch and pray continually, that ye may not be tempted above that which ye can bear, and thus be led by the Holy Spirit, becoming humble,meek, submissive, patient, full of love and all long-suffering; Having faith on the Lord; having a hope that ye shall receive eternal life; having the love of God always in your hearts, that ye may be lifted up at the last day and enter into his rest." Praying continually that you not be temped above that which we can bear is a far cry from a promise that we'll never be tested too hard. In fact, we do get tested to the breaking point and beyond, and I think that's not by accident.
"Everything works together for your good." This one, like the others, is a corruption of actual scripture. The phrase appears repeatedly in scripture, but always as part of a sentence, not a whole sentence. For example, Romans 8:28: "And we know that all things work together for good to them that love God, to them who are the called according to his purpose." And D&C 100:15: "Therefore, let your hearts be comforted; for all things shall work together for good to them that walk uprightly, and to the sanctification of the church." And D&C 90:24: "Search diligently, pray always, and be believing, and all things shall work together for your good, if ye walk uprightly and remember the covenant wherewith ye have covenanted one with another." Clearly it's not a blanket promise the way we sling it around: Don't worry, keep sinning, and everything will work out for your good. Not so. The promise includes some serious devotion to God on our parts to be applicable.
"If you pay your tithing, God will bless you financially." This, of course, is actually part of the old erroneous belief that you can tell how righteous a person is (or isn't) by their money because God's blessings come in coins and bills. If this were true, then Jesus was the sinningest of sinners--he was homeless, after all. The reality is that God does promise us a blessing for paying tithing, but He doesn't specify what that blessing is. (Malachi 3:10 says, "Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the Lord of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it.") Might be money. It might be love, or great ideas, or health, or patience to get through trials. Paying tithing is not a way of manipulating God into making us rich.
"If you come to God with full purpose of heart and repent, he will take your trials away from you." Like tithing is not a way to manipulate God into doing things your way, repentance is not a way of manipulating God into giving you what you want. We are commanded to repent, but as far as I can tell, the results of our obedience are in God's hands, not ours. We can petition Him for blessings we want, but we don't get to make deals with God that if I do _____, you'll do _____. We just have to learn to trust Him anyway, and that's hard when we have no control. If you say this to people, though, they think they are to blame for their trials ("You just aren't repentant enough or you'd get pregnant; you don't have a baby because you are a sinner") or that God is a liar ("I repented and my baby still died.") or that there is cause-and-effect where there is none ("If I repent, my infertility will be cured.")
Ultimately, all of these things we say are really hurtful and, instead of increasing faith (which is what the speaker is intending), they damage people's faith because they aren't true and can't hold up to logic, reason, faith, or the pain of trials.