sorry i guess arabic does not work so here is the verse in english
And do not marry polytheistic women until they believe. And a believing slave woman is better than a polytheist, even though she might please you. And do not marry polytheistic men [to your women] until they believe. And a believing slave is better than a polytheist, even though he might please you. Those invite [you] to the Fire, but Allah invites to Paradise and to forgiveness, by His permission. And He makes clear His verses to the people that perhaps they may remember.221 surat albaqarah
the second verse is about if a non muslim woman becaomes mulsim and comes to islam it forbids us from returning them to the non belivers
even christianity forbids it
http://ag.org/top/beliefs/topics/relations_01_unbelievers.cfm
Deuteronomy 7:3, 4. Here the children of Israel were admonished not to marry the children of Canaan because "they would turn your sons away from following me, to serve other gods." Also after the exile of Israel, Nehemiah pointed out to the remnant (the surviving children of Israel) that the great King Solomon was led astray by his relationship with women who served other gods (Nehemiah 13:26, 27).
they would turn your sons away from following me, to serve other gods
this part also has to why it is not allowed and let me ask you would you want your children to turn away from your god
sister if you trully want to know the truth as we all do i will be more than happy too help