In this case, it's not really borrowing something from another religion, it's borrowing a word to help understand a similar concept that exists. The concept of Hell exists in the Bible - long before the Norse- as a place of damnation, gnashing of teeth, and so forth. The same concept exists in many different religions at many different times. It's the idea of divine punishment for wrongs not corrected in this life - ie, a universal theme. So Christianity didn't borrow it from the Norse - the word Hel instead was used as a translation from the Greek and Hebrew words used to describe a similar place that was already conceptualized in Christian thought.

For more, check out etymology online