SYBOK: Each man hides a secret pain. [...] It must be dragged from the darkness and forced into the light. [...] Share your pain with me and gain strength from it.
That's a little forward, Sybok—we hope you don't use that as your opening line on Tinder. Inadequate game aside, Sybok has deep insight into the ways that people experience pain. We can pretend that it doesn't exist all we want, but deep-seated emotional suffering has a way of biting us in the butt when we least expect it.
J'ONN: Where did you get this power?
SYBOK: The power was within you.
Interestingly, Sybok doesn't take credit for his "miracles" but instead praises his subjects for their openness. This is a way of giving them power and agency over their suffering.
TALBOT: The settlers we conned into coming here, they were the dregs of the galaxy. They immediately took to fighting amongst themselves.
This explains why the settlers on Nimbus III buy into Sybok's religion so quickly. Not only is this a brutal, unforgiving planet, but these folks were misled by the people in charge and now have little hope for better lives. It's a tough position.
CHEKOV: You are under attack by superior Federation forces.
SYBOK: Do you realize what you've done? It wasn't bloodshed I wanted.
Sybok has no interest in inflicting any more suffering on the universe. This is important to remember. Although Sybok does his fair share of bad things on his certifiably insane quest to meet God, he's not the violent wacko he at times seems to be.
UHURA: Scotty, dear, he's not a madman.
SCOTTY: He's not?
UHURA: No. Sybok has simply put us in touch with feelings that we've always been afraid to express.
Even the crew members of Enterprise, who seem to have lived pretty good lives, fall under the spell of Sybok. This suggests that even the most put-together people suffer in their own unique ways, even if that's not always visible from the outside looking in.
MCCOY: How can I watch him suffer like this?
SYBOK: You're a doctor.
MCCOY: I'm his son.
In a terrible double whammy, McCoy's deepest emotional pain surrounds his father suffering from physical pain. His decision to help his father commit suicide to free him from that suffering still haunts him to this day.
SYBOK: That wasn't the worst of it, was it?
SYBOK: Was it? Share it.
MCCOY: Not long after, they found a cure. A goddamn cure.
Poor McCoy. This must be a difficult memory to carry around every day. We can understand why he's so thankful to Sybok for helping him make peace with it.
SYBOK: Each man's pain is unique.
Once again, Sybok says something that isn't totally crazy. That's the odd thing about the guy: half the time, he sounds like an insightful therapist; the other half, he just seems like a deranged YouTube conspiracy theorist.
KIRK: You know that pain and guilt [...] make us who we are. If we lose them, we lose ourselves. I don't want my pain taken away. I need my pain.
Unlike his crew, Kirk has no interest in ridding himself of his most painful memories. Suffering is, as he says, what makes us "who we are." While it's great to reach a place of acceptance about that pain, that's a very different proposition from throwing it away altogether.
SYBOK: I couldn't help but notice your pain. It runs deep. Share it with me.
[Sybok leaps into the mass of blue energy.]
Now this is how you weaponize therapy. Sybok might have dragged Enterprise across the galaxy on a delusional fetch quest, but he proves his fundamental decency by sacrificing himself for the crew.