How is it they no longer knew him or any other after the flesh?
They didn't know Him?
John 20:15-16, "He asked her, “Woman, why are you crying? Who is it you are looking for?” Thinking he was the gardener, she said, “Sir, if you have carried him away, tell me where you have put him, and I will get him.”
Jesus said to her, “Mary.”
She turned toward him and cried out in Aramaic, “Rabboni!” (which means “Teacher”).
John 20:19-20, "On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jewish leaders, Jesus came and stood among them and said, “Peace be with you!” After he said this, he showed them his hands and side.
The disciples were overjoyed when they saw the Lord."
John 20:26-28, "A week later his disciples were in the house again, and Thomas was with them. Though the doors were locked, Jesus came and stood among them and said, “Peace be with you!” Then he said to Thomas, “Put your finger here; see my hands. Reach out your hand and put it into my side. Stop doubting and believe.” Thomas said to him, “My Lord and my God!”
John 21:5-7, "He called out to them, “Friends, haven’t you any fish?” “No,” they answered. He said, “Throw your net on the right side of the boat and you will find some.” When they did, they were unable to haul the net in because of the large number of fish.
Then the disciple whom Jesus loved said to Peter, “It is the Lord!” As soon as Simon Peter heard him say, “It is the Lord,” he wrapped his outer garment around him (for he had taken it off) and jumped into the water."