As much as Jesus was not surprised by the betrayal of Judas, His announcement did shock His disciples. They were not sure who He was talking about. How they were seated is a key factor in clearing up confusion later in the account. They were reclining at the table, leaning on their left hand or arm so the person to the right would be very close, especially at this crowded table. Because of his close position, Peter motions for John to ask Jesus who would betray Him. What we have in this account is Jesus talking to everyone and Jesus having a private conversation with John only.
There may be parts of the Bible that can confuse us or trip us up, yet these questions can be answered with a little study and research. You can trust the Bible because it is clear and does not contradict itself.
Consider: 2 Peter 3:16
