The early Christians had known that Christ’s death and resurrection was meant to call sinners to repentance. Below is a quote from Epistle of Barnabas, ch 5, written by one of the early Apostolic fathers of the late 1st and early 2nd centuries (source here, dating here).
“The prophets, having obtained grace from Him, prophesied concerning Him. And He (since it behoved Him to appear in flesh), that He might abolish death, and reveal the resurrection from the dead, endured [what and as He did], in order that He might fulfill the promise made unto the fathers, and by preparing a new people for Himself, might show, while He dwelt on earth, that He, when He has raised mankind, will also judge them. Moreover, teaching Israel, and doing so great miracles and signs, He preached [the truth] to him, and greatly loved him. But when He chose His own apostles who where to preach His Gospel, [He did so from among those] who were sinners above all sin, that He might show He came “not to call the righteous, but sinners to repentance.”
Remember, Christ’s resurrection, and even our repentance, is a work of God and never our work.