One of the things that jumps out at anyone reading the four gospels as being real accounts of actual events is the prevalence with which devils and casting out devils appears in the text.
At first one might be led to wonder why we don't see the same things today that existed back then.
And the answer is obvious. We do. We don't live on a different planet than Christ and his disciples did. Nor do we think that when the Son of God addressed a devil that he was just a bumpkin who didn't understand what was really going on.
Things haven't changed, but a scientific world doesn't know what to call them.
These days, we prefer to use words like "mental disorder". In Christ's day, a woman who refused to eat because she believed she too fat, and who saw herself in the mirror as being fat, yet was literally starving herself to death would have been correctly described as being afflicted with a devil.
These days we don't like that sort of term. We often prefer science to religion when both come forward with an explanation. And we don't like to refer to the devil if we can help it. But come on. We live in the same world Christ lived in, and we don't think he was just too backward, too much of a country bumpkin, to correctly understand what was going on around him. People are afflicted with devils these days the same as they were in Christ's day.
And just as in Christ's day, with sufficient faith it is possible to cast them out by the authority of the priesthood.
But we have let go of our faith on this matter, and put it into the hands of psychology, a godless substitute for religion. We have a hard time even believing it can be done.
As Christ cast out devils in his day, so they can be cast out today. But not without sufficient faith, as even Christ's own faithful disciples learned:
Matthew 17:14 And when they were come to the multitude, there came to him a certain man, kneeling down to him, and saying,
15 Lord, have mercy on my son: for he is lunatic, and sore vexed: for ofttimes he falleth into the fire, and oft into the water.
16 And I brought him to thy disciples, and they could not cure him.
17 Then Jesus answered and said, O faithless and perverse generation, how long shall I be with you? how long shall I suffer you? bring him hither to me.
18 And Jesus rebuked the devil; and he departed out of him: and the child was cured from that very hour.
19 Then came the disciples to Jesus apart, and said, Why could not we cast him out?
20 And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.
21 Howbeit this kind goeth not out but by prayer and fasting.
There are, any number of accounts of Christ, as well as his disciples, casting out devils. Even in Mosiah 3 an angel announces to King Benjamin that Christ would go forth doing this.
There are also many places where Christ, or his disciples, heal a physical ailment. The text talks about these differently. Examples are the woman who touches the hem of Christ's garment, or the lame man at Bethesda, or the man lowered through the roof, or the man born blind, or the servant of the gentile, or the gentile woman's daughter, and, from the text, we gather there were many, many others. In these cases, it is made clear that the problem is a physical ailment. And sure, there are mental disorders that are really physical ailments. But no, I don't believe that our world is different now than it was in Christ's days, and I think if we could give that statement its full credence we would increase our faith to heal those who are afflicted with devils, instead of pretending that somehow, now, the world is magically different than it was in Christ's day. Our faith and priesthood is sad indeed if it is a a poorer remedy than what psychiatry has to offer.