[OrangeDaisy]

I can't see that demons suddenly disappeared after the first century. So what does a Christian do to rid a loved one of a demon?

All we can do is pray and make use of medical science just as we would any other illness. Christ, his apostles, and the people that the apostles passed on the power to were able to heal and cast out demons, but there is no one left today that has that power.

[petitfour]

I don't believe that. Jesus left us with instructions on how to deal with demons. We just have to have the faith to do it. The Spirit did not die with the Apostles.