I think the community would enjoy discussing this with you. Can you share some more context? Are these people friends and/or family? Co-workers? People you meet in public?
When you ask them questions to better understand what they mean, how do they explain this?
In general, I would think that what you need is not only a conversation but also a community and not only a proclamation but also a process.
That is, the level of change that you seek in their lives is one that will happen as they get involved in a church and a process of spiritual growth. For instance, a weekly Bible study.
For this reason, I think a realistic ‘next step’ for someone in this situation is to see if they would be willing to become involved in a small group environment. If so, as friendships grow tight and their experience of God’s word becomes more important to them, you will also see them coming to a place of greater understanding and desire to know God as he has revealed himself to us.