Scot McKnight posted a devotional excerpt on John 2 from his next book. He ends with this paragraph:
Why did Jesus refuse to commit himself to these people? Because he perceived like no other what was in humans (2:25). His signs divide the audiences (9:16; 11:45-48; 12:37). Some surrender to him because of signs (2:11; 3:2; 6:2; 20:30-31); others accept the reality of the miracle but do not see through it to the identity of Jesus; yet others repudiate him completely. To see his miracles as signs one must perceive the identity of Jesus beyond the material miracle itself. One could say then that sign-faith is a first but not final step in the journey of true faith (Thompson, John, 67–68). True faith abides over time in trusting Jesus who abides over time in nurturing the believer.In other words, necessary, but not sufficient. I fear that's where a lot of "signs and wonders" Christians are at. They see the signs and wonders, and they believe them, but don't press on further to the point of abiding in Christ. They sit by the door, admiring, but don't go "further up and further in" to quote from The Last Battle.
It would make an intersting DMin project for someone to follow up on those who were converted via a signs and wonders presentation and see what percentage stuck with the faith. And then compare it with a control group who were converted via a mass presentation like a Billy Graham crusade.
The Billy Graham people used to say that less than 5 percent of the "decisions" made at a crusade stuck. Do you think the number would be higher in a signs and wonders presentation?
I honestly don't know.