The first reading gives us a picture of the first Council of the Church. What they had to say led to the Council’s decision to let Christians eat foods that all Jews had formerly called unclean.
Peter had been driven to change. It cane about by his one day having seen a sheet descend from the sky. In the sheet he saw pigs and shell fish; and as it came down, he heard a voice ordering him to kill and eat. Peter answered that he had never eaten anything unclean, but the voice told him, “What God has called clean you are not to call unclean.”
Saint James ( the cousin of Jesus, not the brother of John) was the most meticulous of the Apostles in observing Kosher; but when he heard about the holy Spirit descending on unclean Gentiles, he felt bound to say that they might be saved even without observing Kosher.
That first Church Council broke with the past in calling all meat clean. Something similar happened eighty years ago, Vatican II, the last of our Church Councils, broke with the past in allowing us to eat meat on Friday, and to take Holy Communion in the hand.
Conservative Catholics don’t want to change anything from the past, but we must be open to minor changes. Jesus told us the read the signs of the times.” However, we cannot change to any new beliefs that contradict the beliefs of the Church in the time of the Apostles.