Something like that happened at my church years ago. Just as the preacher started the sermon during a Wednesday night service, this obviously wired biker-looking man came in carrying a gun.
One of our deacons saw him and got up to talk to him. It turns out they worked together (this was a blue collar church) and the deacon had been witnessing to him. The man had been binging on drugs and got his gun out to kill himself when he heard a voice telling him to seek that deacon out instead.
The deacon took the gun away from him, and the preacher and the deacons all gathered around him and began to pray for him.
I’m told that night was the start of a turnaround for him. It took a few years, and he fell of the wagon a couple of times, but he eventually got clean and joined a church close to his home.
Won't it be fun listening to billions of such stories?! That's just one of the many reasons we'll have for praising Him.