The pain of a depressed teens are real and we as adults shouldn't ignore them. Even those who trust God usually pass through depression and is for everyone both believers and nonbelievers. David in the bible usually talks about his sadness in the book of Psalms. Being depressed and feeling sad doesn't mean you're serving God, but because all humans have feelings and sometimes you will feel sad.
The bible encourages us to be selfless to those who are suffering and passing through depression. When teens express their depression to us we shouldn't judge them, but instead talk to them and tell them everything will be alright.
Galatians 6:2 says, “Bear ye one another’s burdens, and so fulfil the law of Christ.”
This means parents, guardians, and mentors should listen attentively, offer encouragement, and walk alongside them through their struggles instead of criticizing or ignoring them.