"Then Peter took him, and began to rebuke him, saying, Be it far from thee, Lord: this shall not be unto thee.
But he turned, and said unto Peter, Get thee behind me, Satan: thou art an offence unto me: for thou savourest not the things that be of God, but those that be of men" (Mat 16:23-24 AV).
This is the Peter who, when the chips were down, firmly denied relationship to the Nazarene.
"Whosoever therefore shall confess me before men, him will I confess also before my Father which is in heaven.
But whosoever shall deny me before men, him will I also deny before my Father which is in heaven" (Mat 10:32-33 AV).
You were saying . . .?
Then saith Jesus unto them, All ye shall be offended because of me this night: for it is written, I will smite the shepherd, and the sheep of the flock shall be scattered abroad. But after I am risen again, I will go before you into Galilee.
-- Matthew, Catholic chapter twenty six, Protestant verses thirty one and two
The prophecy had to be fulfilled. All the Apostles left Messiah; John returned first, and he was with the blessed Virgin of Israel, Miriam/Mary the mother of Jesus, God with us. All Messiah's apostles, sans Judas, were saved while they were with Him, just like He said. I'm not sure where you get your teaching. It seems to me you do not believe what this verse says.
While I was with them in the world, I kept them in thy name: those that thou gavest me I have kept, and none of them is lost, but the son of perdition; that the scripture might be fulfilled.
-- John, Catholic chapter seventeen, Protestant verse twelve