When it comes to identifying gospel error and replacing it gospel truth I think of it along these lines:
1. Be a friend, someone people trust and will be honest with.
2. Listen. I mean really listen. You can only help if you have truly heard the heart pain that lies beneath the outward wound.
3. Resist the urge to speak. Instead try stopping and thinking about what they are actually sharing with you. Prayerfully ask God to help you to identify the assumptions they are living by.
4. Respond - for example: "So I'm hearing that you think that you're situation it hopeless, is this right?"
5. If they agree, respond lovingly with the good news and truth of Jesus Christ. For example: "Well I know that things feel terrible right now, and I'm not trying to minimize your pain, but Jesus tells us that no matter what struggles or pains we face He longs to lead us through. Jesus died and rose again so we can have hope in whatever circumstances we face. I've found that when I struggle with hopelessness I can draw fresh hope from Romans chapter 8, especially verses 28-39. Would you mind if I read them with you?"
6. Ask if they would mind if you pray for them and their situation. It is a very rare person who refuses to be prayed for. Pray for God to open our hearts and give us faith that we might believe Him and live by His word.