It has been explained to me in a similar way to this:-

Please note that this was required by God of His people in the Old Testament.
He set up many laws to keep His people pure. As pigs were seen as animals that
ate garbage etc. God called them unclean. Pigs/pork was not an acceptable
sacrifice for the attonement for sins. However, in the New Testament, this law
was "lifted." Because of Jesus' death on the cross (and resurrection),
sacrifices were no longer needed as Jesus was the final sacrifice and faith in
Him was the only way man could be pure before God. It was no longer necessary
for God's people to leave by these strict rules. God declares this once
unclean food clean in the following passage in a dream to Peter.
Acts 11:4-10
"4Peter began and explained everything to them precisely as it had happened:
5"I was in the city of Joppa praying, and in a trance I saw a vision. I saw
something like a large sheet being let down from heaven by its four corners,
and it came down to where I was. 6I looked into it and saw four-footed animals
of the earth, wild beasts, reptiles, and birds of the air. 7Then I heard a
voice telling me, 'Get up, Peter. Kill and eat.'
8"I replied, 'Surely not, Lord! Nothing impure or unclean has ever entered my
mouth.'
9"The voice spoke from heaven a second time, 'Do not call anything impure that
God has made clean.' 10This happened three times, and then it was all pulled up
to heaven again."

This sentiment is backed up by Jesus in Matthew's Gospel (New
International Version)

Matthew 15:10-11
"Jesus called the crowd to him and said, "Listen and understand. What
goes into a man's mouth does not make him 'unclean,' but what comes
out of his mouth, that is what makes him 'unclean.' " "

And again in Matthew 15:16-20
""Are you still so dull?" Jesus asked them. "Don't you see that
whatever enters the mouth goes into the stomach and then out of the
body? But the things that come out of the mouth come from the heart,
and these make a man 'unclean.' For out of the heart come evil
thoughts, murder, adultery, sexual immorality, theft, false testimony,
slander. These are what make a man 'unclean'; but eating with unwashed
hands does not make him 'unclean.' " "

Both Jesus and Paul said that it did not matter what you ate which
included pork. As has been said before, the Old Testament clearly
states that pork is forbidden under the kosher laws which is why some
Jewish people do not eat pork. Christian doctrine however, does not
accept kosher food laws for the reasons noted above.