Are Christians Allowed to Eat Pork or Seafood?

A large part of Singaporean life and culture revolves around food (unfortunately, because gluttony is a definite temptation here), and it's common for believers in Singapore to have fellowship with one another over a meal at the hawker's centre of food court, say after the church service on Sunday.

Some young believers, however, who have started reading the bible on their own, may have conflicting feelings about eating pork and seafood, since there are prohibitions over the consumption of these things in the book of Leviticus (chapter 11; NIV):

⁷ And the pig, though it has a divided hoof, does not chew the cud; it is unclean for you...
⁹ “‘Of all the creatures living in the water of the seas and the streams you may eat any that have fins and scales. ¹⁰ But all creatures in the seas or streams that do not have fins and scales—whether among all the swarming things or among all the other living creatures in the water—you are to regard as unclean. ¹¹ And since you are to regard them as unclean, you must not eat their meat; you must regard their carcasses as unclean. ¹² Anything living in the water that does not have fins and scales is to be regarded as unclean by you.

For me personally, I have no issue about eating pork or seafood (in moderation, of course).

However, if a young believer has an issue (due to the verses of scripture cited above), my advice to him/her would be to refrain from consuming these things.

My advice would be based on the following principles found in Romans 14:

¹⁴ I am convinced, being fully persuaded in the Lord Jesus, that nothing is unclean in itself. But if anyone regards something as unclean, then for that person it is unclean...
¹⁷ For the kingdom of God is not a matter of eating and drinking, but of righteousness, peace and joy in the Holy Spirit

Meanwhile, it's interesting that the Apostle Peter had a vision (in Acts 10) regarding eating "unclean" things. Although the underlying message of the vision was not about food per se, it is important to note that the apostle was "hungry and wanted something to eat" when he had the vision, and that it was the Lord Jesus that had spoken to him during the vision:

⁹ About noon the following day as they were on their journey and approaching the city, Peter went up on the roof to pray. ¹⁰ He became hungry and wanted something to eat, and while the meal was being prepared, he fell into a trance. ¹¹ He saw heaven opened and something like a large sheet being let down to earth by its four corners. ¹² It contained all kinds of four-footed animals, as well as reptiles and birds. ¹³ Then a voice told him, “Get up, Peter. Kill and eat.”
¹⁴ “Surely not, Lord!” Peter replied. “I have never eaten anything impure or unclean.”
¹⁵ The voice spoke to him a second time, “Do not call anything impure that God has made clean.”

My question is this:  if it were even wrong or sinful to eat "unclean" animals, would the Lord Jesus Christ "tempted" Peter to do so? I do not think so.

But why then does the book of Leviticus prohibit the consumption of pork or seafood?

Barnabas, a leader of the early church, gives an explanation in his letter (although Barnabas' letter has not been included in the bible, it serves as useful commentary).

Barnabas suggested that when Moses gave these food prohibitions to the children of Israel, it was as if Moses was speaking a parable and that it was the transmission of spiritual principles that was actually intended:

But forasmuch as Moses said; Ye shall not eat seine nor eagle nor falcon nor crow nor any fish which hath no scale upon it, he received in his understanding three ordinances.
Yea and further He saith unto them in Deuteronomy; And I will lay as a covenant upon this people My ordinances. So then it is not a commandment of God that they should not bite with their teeth, but Moses spake it in spirit.
Accordingly he mentioned the swine with this intent. Thou shalt not cleave, saith he, to such men who are like unto swine; that is, when they are in luxury they forget the Lord, but when they are in want they recognize the Lord, just as the swine when it eateth knoweth not his lord, but when it is hungry it crieth out, and when it has received food again it is silent.
Neither shalt thou eat eagle nor falcon nor kite nor crow. Thou shalt not, He saith, cleave unto, or be likened to, such men who now not how to provide food for themselves by toil and sweat, but in their lawlessness seize what belongeth to others, and as if they were walking in guilelessness watch and search about for some one to rob in their rapacity, just as these birds alone do not provide food for themselves, but sit idle and seek how they may eat the meat that belongeth to others, being pestilent in their evil-doings.
And thou shalt not eat, saith He, lamprey nor polypus nor cuttle fish . Thou shalt not, He meaneth, become like unto such men, who are desperately wicked, and are already condemned to death, just as these fishes alone are accursed and swim in the depths, not swimming on the surface like the rest, but dwell on the ground beneath the deep sea.

Hope that helps somewhat.