He disagreed with the professor's theory calling him a moron

[Tarheel]

Yes sir of course.

But this sentence is grammatically correct right? :

Professor Johnson objected strongly to the professor Smith's latest theory calling him (Smith) a moron.

After another look, I would delete "the" and say "Professor Smith's latest theory".

 

[GoesStation]

After another look, I would delete "the" and say "Professor Smith's latest theory".

It still needs a comma.

 

[Tarheel]

It doesn't matter what sex ems is. It's impolite to assume that any unknown person is male.

The possessive Professor Smith's does that.

Always mark words your text discusses by surrounding them with quotation marks.

Or by putting them in italics.