Why do the oldest NT mcripts use specifically greek pagan words, eg. words like 'hades'?

Hades was the murky underworld where the gods sent people and other gods who seemd to go. They could get out of there too. The word 'Hades' appears in the oldest NT mcripts many times. Why is god's word including specifically pagan terms with specifically pagan meanings that don't match what christianity teaches of the afterlife?