John 13:36

Simon Peter saith unto him, Lord, whither goest thou? Jesus answered, Whither I go thou canst not follow me now; but thou shalt follow afterwards.

Peter was determined to follow Jesus both to prison and to death, and there is no doubt of Peter's sincerity. What he did not at that time realize was that the power to do such a thing is not resident in men but comes only from above. The access to such heavenly strength would come to Peter only after the victory of Jesus upon the cross had made it possible. In his reply, Jesus addressed Peter's intentions, not his question, and pointed out (1) Peter's present inability to follow the Lord, and (2) the full ability of Peter to do so after the enabling sacrifice on Calvary had been made.