John's baptism was "for the remission of sins" (salvation) but it took place before Christ shed His blood. This must mean those baptized with John's baptism had their sins remitted in promise, had salvation in promise looking toward to when Christ did shed His blood then their sins were remitted.Nope - those WHO DIED IN FAITH (that God would provide a way) went to "Abraham's Bosom" - to WAIT until the provision for them would be made on Calvary - thousands of years (for some) in the future. It's all in the Bible.
So those under the OT law before Christ shed His blood possessed salvation in promise looking toward Calvary. Since God cannot lie and break His promises, those who lived faithfully under the OT law, their salvation was just as certain as those today who live faithfully after Calvary.