The good news is that a lapsed/apostate person is still the object of God's loving affection, and He wills that they be restored to the Body through repentance, that they might know again the refreshment that is in Christ.
Donatism and Novationism is rejected heresy; Christ is the Good Shepherd.
We don't need to time-travel, we simply bear witness to Christ, and the Holy Spirit faithfully moves and acts and works. He will, as faithfully as He called us to faith in the beginning when we were baptized and first believed, will always call us to faith--even when we have fallen into apostasy and cast away the hope of our salvation.
-CryptoLutheran