Scripture to back that up is found where??
Please suffer me to be a bit cheeky metmom....
John 13:19 Now I tell you before it come, that, when it is come to pass, ye may believe that I am he.
The apostle Peter went from denying Christ in fear to preaching in public on pain of death (and eventually,actual death)
I think the fact that Peter saw with his own eyes the risen Christ actually swept away completely any and all double mindedness,fear,doubt etc.It was then the mountains started moving for him.
In a very similar vein,if we are indeed living in the very last days of this age then I believe and hope a very similar thing is going to come upon believers.
God is going to equip those that are 'watching' in a big way.He told us many things beforehand so that when we see,because we are 'watching' then we will believe.
There may be literally millions of 'Peters' right now who are passionately believing on Jesus against everything in the world and even themselves and are still being hindered by the world and themselves.
Perhaps there will soon come the time when we no longer need to cry out "Lord I believe,help thou my unbelief" and then the sky will be blotted out by flying mountains and the beaches will be covered in washed up herds of swine.
Assuming the rapture to be pretrib,it would go some way to explaining why so many (that they can not be numbered)will turn to Christ on pain of loosing their heads after spending so long either holding Him at arms length or outright denying Him.
They and of course we have been told "before it come" in order that "when it comes" we may believe.
Please excuse the rant,hope it made some sense.
Grace and peace to you both!