The testimony of faithful missionaries like Dave and former Muslims coming to Christ should be enough to convince us, but we also have the testimony of scripture:
Joel 2:28-29 (NIV)
“And afterward, I will pour out my Spirit on all people. Your sons and daughters will prophesy, your old men will dream dreams, your young men will see visions. Even on my servants, both men and women, I will pour out my Spirit in those days.
Until next week, keep watching!