Everyone who visits this blog should understand that there is not enough evidence to support the idea that alien spacecraft have visited Earth. However, you can find tons of eye-witness testamony regarding UFOs and UFO abductions. Why is this so?
Part of the reason for people believing they saw a UFO is due to a psychological phenomena known as argument from ignorance. Someone sees bright lights in the sky, they don't know what it is, so they say, "It must be a UFO!" Their thought processes should have stopped after they realize they don't know what it is, but the human mind craves understanding of the world. We sometimes impose improbable and unlikely rationales simply because our minds cannot stand not understanding.
The same is true of God. Plenty of people claim to have experienced miracles by the hand of God, but as evidenced by UFO beliefs, eye-witness testamony is a horrible form of evidence. Here's a typical story of a theist explaining a miracle:
Theist: "One time, I got in a car accident. I should have died, but God saved me. That's how I know God exists; through miracles like that in my life."
The statement above falls prey to the argument from ignorance phenomena. The theist got in a car accident, doesn't know why he survived, but proclaims divine intervention as a way to understand what happened.
So whenever someone proclaims to have seen UFOs or miracles from personal experience, you can remind them of how our brain tricks us through argument from ignorance.