I think most people can understand the pain of losing a close friend or family member to drug addiction, but a less understood pain is the loss of someone to extremist, cultlike religion.
To be clear, I'm not saying one is "worse" than the other. Drug addiction is certainly more dangerous to physical health and is more likely to land people in legal trouble, but religious fundamentalism can also be deeply harmful. It erodes at individuality, curiosity, creativity, and compassion. It replaces a fully realized human being with a set of prepackaged values intent on conquering all other worldviews. Essentially, it's a virus that masquerades as a cure. I don't believe that religion itself is a virus. It can be practiced in a healthy way. But fundamentalism is never healthy, either to oneself or to others. It also seems to have more social support than narcotic addiction because it comes with the veneer of a moral high ground--not only a sense of superiority over those who are not religious, but also over those who are spiritual but not obsessive about it.
I have watched as unique, brilliant, funny, completely benevolent people have succumbed to drug addiction and religious extremism alike. It's heartbreaking in both situations. A cherished old friend of mine now believes I'm going to hell because I don't think you have to be Christian to be a good person, nor do I believe that non-Christians are damned, and because I am bi. It's so chilling to look at someone you used to know so well and see that they no longer recognize you, and vice versa. To know they sincerely believe you are destined for a place of neverending torment and that you will deserve every moment of it because you're not straight and you don't share their beliefs. Yet they tell you in the same breath that they "love" you. How can you love somebody if you believe that the ultimate judge of the highest good has already deemed them worthless? If you think they deserve to be tortured? I'm not only disturbed on my own behalf, but also on account of the way they're treating other people. The constant proselytizing, the vandalism of others' sacred spaces with fire and brimstone. The way they behave toward the LGBT community. I have always found the idea of anybody ever being designated to hell to be abhorrent, and reject it because it could not coexist with any kind of goodness in the world.
Hopefully they will come around eventually. Hopefully their emotional and intellectual immune system will fight off this virus and they'll be back to themselves someday. This is my most urgent wish right now. There are few things as painful as watching a beautiful person deliberately suffocate everything that makes them who they are.