John 6:60

This spake He, &c. Christ taught these things, not in secret, not in a corner, but publicly in the synagogue in the presence of the Scribes, the Priests, and the whole people who had flocked together. For the synagogue was a sort of church.

In Capharnaum, "where," says S. Chrysostom, "He had done so many miracles, and where He had the best right to be heard. Because the things which Christ spake concerning eating His flesh, and His being about to raise us up from death unto life eternal, seemed paradoxical and incredible to the Jews, He wished to proclaim them from that place, where by His many miracles He had gained faith and authority for Himself and His doctrine."