Therefore comfort one another with these words.
While this gentle assurance from1 Thessalonians 4 was given to remind one another that Jesus will return I think this is given to address a more fundamental anxiety of aloneness that can take hold of our hearts.
So much counsel today is filled with spot-on truth, but alas it is given in the form of a scripture pill intended for self-medication. The problem occurs when such a pill designed to medicate this sense of aloneness and fear is given to be taken alone! (Ah, modern Christianity where every Christian must walk their own private isolated spiritual path...)
So I think there might just be a second way to read "Comfort one another with these words" other then 'point out this truth.' Implied in this verse, is a patient and tender fellowship, even a companionship. It is embodying the hope of Jesus' closeness to us, by choosing to be close to one another through fear and loneliness.
It is not only stating the obvious "I'm only human---I can't help you so take your fears to Jesus and ask him for the strength to keep living' but instead demonstrating that power by saying "Share your fears with me, because I am not going anywhere." Confidence in Christ is conveyed in that position.
It is not despising weakness as strange, nor it is it dismissing it as invalid. It is approaching the very real presence of fear in the hurting person, with the assuring fearlessness of love. It is not about a correct recital of the facts of God's comforting presence only, but a demonstration of this truth in our own comforting enduring companionship.
I do understand that none of what I am saying is a cure...and even if we stand by one another, years may continue to roll by without hint of resolution. Yet, inspite of my fairly decent awareness of scriptures that address fear, I've had the most effect in comforting fearful people by giving the hours, weeks, and even years of compassion with them until they are strong enough to walk again. This is not to say that scripture is impotent, but that God's word is not simply a manual for fixing people in the manner we sometimes approach it as we flip through the blessed pages looking for 'answers'. If we wish someone to see how Perfect love casts out fear, we might need to find such perfect love, not in the pages of scripture, but in the 'tablets of our own hearts'. (Which clearly you have, as evidenced abundantly by the tender burden you carry for your son!)
I once had a close friend who struggled with work-a-day employment. He literally had a kind of claustrophobia when it came to working for people. Invariably his fear and mistrust of employers would function as a kind of self-fulfilling prophecy where they would end of pushing him out so to speak.
At first I felt this need to 'fix' him in a hurry. This verse, that verse...this sermon, that book. Yet, grace was given to me to simply walk this through with him with no timeframe placed upon the outcome. I can remember nights when he could not sleep because he was filled with so much fear...I would pray with him over the phone that even as he slept he would know that Jesus is at his bedside watching over him. He who keeps you will not slumber. Behold, He who keeps Israel Will neither slumber nor sleep. The LORD is your keeper;
Praise God, this very good friend has been 'healed' of this burden. My part of his journey along this path took almost 7 years...his own part took decades. There was no steady vector of progress to encourage any of us along the way...only a sudden clearing at the end of the dark forest he seemed lost in. He and his faithful supportive wife are the most hopeful they have ever been. His confidence and vision for providing for his family is strong...and now inspiring me! (As an added bonus, his poor credit over the years has prevented him from acquiring any serious debt, ironically positioning him financially better then most middle aged men he knows---their career success has been wasted on big houses, cars, and credit cards! God is wiser then we are.)
In conclusion I realize I haven't provided a scripture "pill". Your love for your son, and companionship is going to go the furthest to building him back up. There might be times you feel helpless, but it might just be that his inability to see and trust God in some area is helped by his ability to see you. And taking hold of the precious truth of God's nearness to his children is the surest road to peace and security within the fractured and fragile heart that must experience bruises and cuts in this hostile world.
Many men want to throw exhortations of toughness and courage at another man who is fearful, but I have learned from the lamb of God that tender love is the most unafraid power in the universe. Finally taking hold of the love of God may seem too soft and irrelevant as a cure for debilitating anxiety and fear, but I have seen that when we at last take hold of God's love, the chains of fear begin to fall away. It's unyielding strength is akin to a tender dandelion that pushes it's way through concrete sidewalks. It does not push or claw...it simply lives.
Your son is blessed to have a mother who can feel such tender burdens for him.
Blessings,
MC