Today, the first reading that the Church gives to us in the Mass is Acts 11:1-18. In it, Peter has been consorting with Gentiles (non-Jews)--something taboo for pious Jews at the time because the ritual purity laws forbid it. He explains that a vision was given him, showing him all sorts of unclean animals and a voice from heaven telling him to kill and eat the animals. Peter replied like any faithful Jew would have, refusing to eat what was unclean. The voice replied: “What God has made clean, you are not to call profane.”
What goes unmentioned here is the fact that the animals were considered unclean for the sake of ritual purity--primarily for the sake of purely offering the sacrifices in the Temple. Some have even argued that the clean animals were the same as the animals that neighboring pagans had worshipped as gods and that the slaughter of the clean animals was the slaughter of the pagan gods as a way of keeping Israel pure from the worship of false gods. Dr. Hahn treats this well in his book A Father Who Keeps His Promises:
The Israelites had to fight a protracted war against idolatry, which they were commanded now to wage by daily animal sacrifice, among other things. Within the Father's remedial program lay a subtle strategy. On the one hand, Israel couldn't slaughter—or eat—the animals that the Egyptians sacrificed to their gods; they were declared unclean. On the other hand, Israel had to slaughter and eat the animals that the Egyptians venerated but never sacrificed; they were clean. 
The entire book of the Acts of the Apostles, however, takes place after Jesus’ resurrection. Jesus’ sacrifice, beginning in the upper room and consummating on the cross, had already been performed. That for which the Temple sacrifices were called has been fulfilled by the one true sacrifice. The Jewish Temple has become sacrificially useless--signified by the tearing of the veil from the top down (Matthew 25:51, Mark 15:38) commonly understood as the tear coming from God, not man and the tear representing the fact that the Temple holy of holies is no longer useful. The veil used to cover it because its holiness was only to be seen by the high priest on Yom Kippur, the Day of Atonement. Full Atonement had been made by Jesus’ sacrifice. There was no more need for the Jewish Temple because its sacrificial system had been fulfilled by the new definitive sacrifice.
With the replacement of the old sacrificial system (in fact, the entire Old Law, save what is contained in the Natural Law) by Jesus’ new sacrifice, the ritual purity laws were also fulfilled and replaced. Jesus’ sacrifice established a new covenant, with a new sacrifice and a new priesthood. God has made all the animals clean and He has opened membership among those people He calls His own to the Gentiles. This is particularly relevant for me and bacon. I don’t come from Jewish descent, so only by Jesus’ opening up to the Gentiles am I able to participate as a member of the people of God during this life--and only by His fulfillment of the Old Law has He made bacon (and all previously unclean foods) clean again, so, enjoy your bacon and thank God for revealing to us (through St. Luke's recollection of our first pope's explanation) that these foods are no longer off limits. Thank God even more (those of you not from Jewish descent) that we are able to be a part of the Catholic Church and receive, from her, the graces to be drawn into an ever-deepening union with God.