The opening to this letter is tender and encouraging. God is the God of all comfort and a compassionate Father. Yet, He does not keep us from affliction. Rather, he comforts us as we go through it.
Comfort, like any grace, does not come to us as an end in itself, but comes to be passed along. Comfort is not the end of the journey, but something that happens along the road.
The promises of God are "yes" in Christ Jesus. The Holy Spirit verifies the "yes". It is sad, then, that so many people hear "no" when they hear Jesus. I imagine some of the "no" comes from the way Jesus is communicated and some comes from the way every human is naturally wired.
Paul doesn't Lord it over their faith but, I love this perspective, works together for their joy! We should all have someone working together with us for our joy. That's what I want to do for people.