The logic is not necessarily flawed, but it is incomplete without a few incorrect assumptions:

The professor argues that there can be no god because A) there is no observable evidence and B) Evil and hatred exist (supposedly things that are opposite to god's attributes and which seem to contradict his infallible, omnipotent, creator-of-all-things type of vibe). The student gives analogies where faith is necessary for everyday things in life (an argument against contention A) and then goes on to illuminate the issue with his suggestion that evil is only the absence of god, as dark is to light (an argument against contention B). The logic seems to be sound as far as I can tell up to here.

It is left to the reader to assume that a valid explanation for the presence of evil in this world is that hatred and such things are resent due to a lack of faith, a lack of god's presence, godlessness, ... something along those lines. However, if one thinks of some examples of evil deeds committed in the world (this part may be slightly more subjective), one does not need to read the history books too long to stumble across the Spanish Inquisition, residential schools in Canada, molestation of children by Catholic priests, terrorist attacks in the name of various gods, the Crusades, etcetera. Terrible atrocities have been committed in god's name (whichever it is) and I think that OP and any other believer/non-believer would have trouble denying that those men and women responsible for orchestrating such events (and their many religious followers that were necessary to do so) were headstrong in their beliefs and did not exhibit a stark lack of faith. Evil is carried out in god's name just as it is carried out otherwise.

To believe in god is one thing. I do not believe that anyone will have much luck proving or disproving that notion in itself. If one personally believes one has found an intangible presence in the universe that they with to describe that way (be it via drugs, meditation, or trauma), I would be completely supportive. I may even be one of those people. I have not made up my mind after many years of wondering. However, to subscribe to an organized religion (someone else's religion) based on the same stories and book(s) that spurred countless acts of rape, torture, excecution, violence, oppression, and slavery is indeed evil.

I believe the tendency to have/search for faith is natural in curious humans and I believe so too is the desire to exploit such a tendency for selfish purposes. It would almost be absurd to imagine a world without religion, where at no point in history was a single con-man successful in convincing the masses of one thing or another for one purpose or another.

TL;DR: OP contends that evil is a symptom of godlessness. I contend that much evil in the past has been committed under completely opposite circumstances.