"It was never lost needing to be 'rediscovered'. A close reading of history shows that there were small Christian churches throughout history who have believed The Gospel."
Please don't confuse Calvinism/predestination with "the Gospel". Paul certainly didn't.
"Now I would remind you, brothers of the gospel I preached to you, which you received, in which you stand, and by which you are being saved, if you hold fast to the word I preached to you— unless you believed in vain. For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures, and that he appeared to Cephas, then to the twelve. Then he appeared to more than five hundred brothers at one time, most of whom are still alive, though some have fallen asleep. "
One of the striking weaknesses of Calvinism is that they can only find one reputable Church father (Augustine) to look to for support in over 1500 years of Church history.