One word to call people that attach their feelings to a concept

You could use the word zealot:

zealot: a person who is fanatical and uncompromising in pursuit of their religious, political, or other ideals.

If I said someone was an Object Oriented Programming zealot, you would expect them to be very defensive in the face of perceived attacks on or disagreement with OOP principles.

I feel this word captures the essence of the behaviour you describe but without being as specific about the personal identification reasons for the behaviour as you are in your question.

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Possible related words include (slightly less pejorative) fanatic or (more hyperbole) militant.

For example, I would go along with being described as a Haskell fanatic or a maths fanatic, but would feel over-criticised if you called me a zealot. I would feel you were being very unfair indeed to describe me as militant! There is a fanatic badge on Stack Exchange (for visiting a site for 100 consecutive days) but there's no zealot badge, as badge names are deliberately chosen to be positive.

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Interestingly zealot has negative connotations, whereas the root form, zeal, does not:

zeal: great energy or enthusiasm in pursuit of a cause or an objective.

I think ideologue fits the bill here. It is essentially someone who is wholly committed to a certain philosophy, concept or ideal.

ideologue: an adherent of an ideology, especially one who is uncompromising and dogmatic.

One word to call people that attach their feelings to a concept: cathectic

Cathect verb (used with object) Psychoanalysis. to invest emotion or feeling in (an idea, object, or another person).

The mentality you've described is an example of chauvinism:

1.Exaggerated or aggressive patriotism.

1.1 Excessive or prejudiced support for one’s own cause, group, or sex.

A chauvinist will typically be sentimentally/emotionally invested in whichever ideology they subscribe to, and will often react aggressively if challenged on the issue.