This can also put many things into gray areas such as end of natural life. I had an aunt a devout RC who in her final months gave up eating. She was elderly and lived a full life. Nothing tasted good and she lost all desire for food. I see that falling under a dismissal of ones spirit being into GOD's hands. I believe a person can literally will themselves to die even without the physical act of suicide. I also think to some who attempt it for whatever His reasons GOD denies it to them.
A person thinking of suicide needs mental health help well beyond what most clergy in any church can give or are qualified. There is a very real danger of saying the wrong thing like Brother if you only had more faith etc. This only compounds their problems and they see it as more failure on their part and give up. Even the most skilled therapist loose a certain percentage and I do know several therapist who are Christians and in their therapy use Biblical principles for healing and finding peace.
Not even preachers are exempt from falling into the despair to desire to take their own life. It's one of the most difficult things as therapist deals with.
The way to reach them is to explain the pain they leave to others first. Give them a reason to want to live not out of fear but rather they are still needed here amongst the living.
Even Christ had to step away from the world around Him as it become a bit much to deal with. He would either by himself or with the 12 retreat for a period of time to let the mind, body, and spirit rest. I learned about that the hard way when I was going to the hospital every night to see my then girlfriend. The mind in extreme fatigue can play some nasty tricks. If you don't give it rest it will literally make you. I'm Baptist myself but a Nun explained to me why I had became numb in all my feelings. She told me go home and rest and take a few days to myself. She was right.
One day we were talking and she said she had a problem that she couldn't even talk with me about and was in some distress.
I suggested to her that I take her to my church and she could go into the confessional and talk with the priest. I told her to start by telling the priest she was not catholic but needed desperately to talk with someone. I also explained to her as she knelt, she would hear the sliding of a the cubical door that meant the priest was now listening to her..
I waited out in the church. She was in there for some time, she never talked to me about it which was fine, but she also never mentioned a problem she could not talk to anyone about....I have guessed that whatever the priest told her must have helped. And she had the confidence of knowing that the priest would never talk about it outside of the confessional either...cross religions can help one another if we let it.