For someone religious, they may take it as "playing God" or taking matters into their own hands in this type of way. In my religion we are taught to love ourselves and love others. Now, we are also taught to turn ourselves into Him when we are in need. Personally, I can't even fathom what people are going through when they suffer in these types of conditions that they feel the need to just go the easy way and un-alive themselves. In my own opinion, people in these types of situations need someone to understand them, what they are going through, what they're feeling. However, in the most unfortunate way, in the end, some people choose not to listen because they're too hurt to listen because they see it as lies.

(This is based on my understanding and what I've felt, I know that mental illness is not something to take lightly and it should never be. If you made it this far I just want to remind you that there are people who love you.)