What is the biblical basis for the theory that Christians should not eat pork? I've been tormented by hearing from friends and such (that aren't religious) that they've heard and been told eating pork and chicken is a sin. And that it means going to hell....which is obviously out of proportion. 

My Question: where, how, and why did this come about? Was it haters? Or people against Christianity totally? Or what? 

Note: I know it's of a muslim culture/religion but not christian that I am aware of. At least not of a religious law like the 10 commandments.
The Scriptural basis for the Jewish diatary laws is Leviticus 11.
In particular, verse 7 says: 


  And the swine, though he divide the hoof, and be clovenfooted,
  yet he cheweth not the cud; he [is] unclean to you.


(This and all following quotes are taken from King James Version, for consistency.)

These admonitions are repeated in Deuteronomy 14; particularly,
verse 8 says:


  And the swine, because it divideth the hoof, yet cheweth not the cud,
  it [is] unclean unto you: ye shall not eat of their flesh, nor touch
  their dead carcase.


This is all well and good, but up until here we are talking of the
Old Testament and Mosaic Law. Coming into the New Testament, the
Evangelists (Matthew 15:1–20, Mark 7:1–23 and
Luke 11:37–41) report Jesus' words:


  Not that which goeth into the mouth defileth a man; but
  that which cometh out of the mouth, this defileth a man.


Of course, in this case it was an issue of the disciples not washing
themselves before eating bread, but it establishes the precedent for
the question described in Acts 15, which has been described as the
first Ecumenical Council, or the Council of Jerusalem:


  
  And certain men which came down from Judaea taught the brethren,
  [and said], Except ye be circumcised after the manner of Moses, ye
  cannot be saved.
  When therefore Paul and Barnabas had no small dissension and
  disputation with them, they determined that Paul and Barnabas, and
  certain other of them, should go up to Jerusalem unto the apostles
  and elders about this question.
  
  
  (...)
  
  
  And the apostles and elders came together for to consider of
  this matter.
  And when there had been much disputing, Peter rose up, and said
  unto them, Men [and] brethren, ye know how that a good while ago
  God made choice among us, that the Gentiles by my mouth should
  hear the word of the gospel, and believe.
  
  
  (...)
  
  
  Wherefore my sentence is, that we trouble not them, which
  from among the Gentiles are turned to God:
  But that we write unto them, that they abstain from pollutions
  of idols, and [from] fornication, and [from] things strangled, and
  [from] blood.
  


These abstinences referred to in verse 20 are the so-called Noahide Laws,
which are required of all the sons of Noah, i.e., everybody, since all
men who were not sons of Noah perished in the Flood. Therefore, there is
a sound Scriptural basis to argue that Christians are specifically
allowed to eat pork.

That being said, there is nothing that prevents a Christian from deciding
to follow these laws anyway (as Paul himself did, check Acts 21:26). This
gives rise to the so-called Jewish Christianity, who are Christians who
confess the divinity of the Christ while at the same time keeping the 613
Jewish mitzvot.

Finally, I think that your Muslim friends' reactions are probably due to
a misconception that Jews and Christians are bound to their halal
dietary laws, or that they consider that anyone who violates the commandments
given to them in the Quran and/or the Sunnah are going to earn eternal
condemnation, regardless of whether or not they ever converted to Islam
in the first place.