Is there such a thing as "atheist fundamentalism"?

I think I can see your exact blunder now.

You think:

Since concepts only exist in our brain and do not entirely represent reality, then certain concepts cannot be addressed by science...

logical leap in 3.. 2..

Therefore all these concepts like love, etc cannot be addressed by science.

Your mistake is that you are not correctly separating concepts that represent existing things and concepts that represent non-existent things.

Non-existent things: Dragons, God, Fairies, Spiritualism & leaps of imagination from things we observe.
Existing things: Things that can be observed.

And even purely fictional things are grounded on physical concepts and ideas. There is really nothing you can do to get away from science.

You act like the issue is that simple.

It would be GREAT is it were.

Do intangible things exist?
To address this question we have to address the material components.

Define exists.
1. to have being or reality; to be
2. to eke out a living; stay alive;
3. to be living; live
4. to be present under specified conditions or in a specified place
5. (Philosophy) Philosophy
a. to be actual rather than merely possible
b. to be a member of the domain of some theory, an element of some possible world, etc.
c. to have contingent being while free, responsible, and aware of one's situation

Define intangible.
As an adjective
1. Incapable of being perceived by the senses.
2. Incapable of being realized or defined.
3. Incorporeal.

As a noun
1. Something intangible, especially an asset that cannot be perceived by the senses. Often used in the plural: intangibles such as goodwill and dedication.
2. Law Incorporeal property such as bank deposits, stocks, bonds, and promissory notes. Often used in the plural: a state tax on intangibles.

For the purposes of this argument, we will assume (5. (Philosophy) Philosophy (a. to be actual rather than merely possible)) and (1. Something intangible, especially an asset that cannot be perceived by the senses.) apply to your position inclusively.

So to answer your question in the context I've provided, given the material facts surrounding the definition of the words you've used, no.

Intangible things do not exist because they can be *DENIED* and their existence is contingent on being MORE then possible. If you can offer nothing more then "possible", then the answer is no.

Yet, emotions do exist. They must not be intangible then!
Fact of the matter is, they aren't intangible. They are represented in the tangible by chemical processes.

Next question, please.