They say, " Allah has taken a son." Exalted is He! Rather, to Him belongs whatever is in the heavens and the earth. All are devoutly obedient to Him,
The translation of "NAY" is of the word "Bal" .
Here the word "Nay" - equals to - "But, Rather". . . and not "no" - as you thought.
http//dictionary.reference.com/browse/nay?s=t
Personally I am 100% against the free-minds translation and do not hold it to be accurate at all.
I fully agree.
SLM