Here's the one that really gets me, which is what started me thinking down this path in the first place: it's when you're going through a tough season in your life and someone has the nerve to say to you, "God must want to use you for something big."
"God's got plans for you!"
"Of course you're having a tough time. The devil is trying to stop the big, amazing, glorious thing God wants to do with your life."
But that's not helpful.
Nor is it biblical. It's another one of those things we have kinda sorta attached to Job, to make us feel better about his story, I guess, but even then, it doesn't accurately reflect the story. God didn't want to use Job; God was using Job. Job was a blessing to everyone around him.
In fact, there is not a single character in all of Scripture, not a single person in God's story, who is afflicted by the devil because God was trying to use them. Not one. And there are plenty of persons afflicted by the devil.
Look at every single one of the demon-possessed individuals in the Gospels. Look at them. Look at the girl in Acts. Not once does Jesus (or Simon or any other disciple/apostle) cast out a demon and declare that that person has come under spiritual attack because God was trying to use them mightily. Not once.
Now, here's where it can get a little tricky. Because Jesus does say on at least one occasion that the affliction He's just healed is so that God can show His glory, but pay attention - He doesn't mean it the same way that we try to make it sound like He does. Not even close.
There is just simply no biblical truth to the notion that when your life is a struggle, it's because the devil is trying to keep God from using you and you are therefore stuck in some kind of massive, invisible spiritual battle.
When God wants to use Gideon, Gideon is the one who lays out the dry fleece.
When God calls Isaiah, the prophet simply says, "Here am I!"
When God comes to initiate Samuel into the priesthood, He comes as a voice in the night calling out to the man.
The evil spirit that came upon Saul (Old Testament Saul) came after God had decided not to use the first king to establish the line of royalty. In other words, after God was done using Saul. (Sort of. It took a bit longer after that.)
The point is - wherever we got this idea that trial, trouble, and struggle indicate some kind of incredible spiritual battle and the darkness of the devil because of God's great plan for us...it isn't from the Bible.
Which means that if nobody ever said this ugly non-truth again to someone struggling, it would actually be very okay.