They, each one, merely learns Greek, studies all the extant writings of the time, immerse themselves in the the teachings of living students of the Apostles, consult the Holy Spirit, and...
Agree with Martin Luther, subtractions and additions all inclusive.
Voilá!
Luther’s problem was he remained “too Catholic.” Don’t you know? (Sarc.)
Baptismal regeneration, private confession and absolution, priestly vestments and candles, the real presence of Christ in the Eucharist, sacramental grace, etc.
Catholic bad. Iconoclast good.