Not everyone is comfortable having a Bible study with a non-Christian. Everyone is able to pray for lost people. Start with what people can do and are willing to do and eventually they will be willing to try new things. If they are willing to write a note to a new person, ask them to write. If they are willing to have lunch with a visitor, ask them to do that. If they are able and willing to study with a non-Christian, take the time to line up that study. If time is a problem, have them do it in an unused room during Bible class on Sunday or Wednesday. We may not start with 100 people who are willing and able to study with non-Christians but if you can get them to start by praying for the lost and for specific lost people they know, in time they will get comfortable with more. Learning to evangelize is a process of maturation that comes only by experience.
Seeing is believing, they say, but not with miracles. There are people who see miracles who deny it. Just ask