Can we put 'a' in front of uncountable nouns like love, hate, peace?
If you modify a noun with an article (the, a, an), it basically alters the meaning from general to specific.
"Book" means "book as a general entity.
"A book" means "one book out of several"
"The book" means "a specific example of book as a general entity"
In the case of the non-countable nouns you've listed above, the inclusion of an article conveys the exact same idea.
"Love" means "love as a general concept"
"A love" means "one example of the concept of love"
"The love" means "a specific example of the concept of love"
"Peace is worth fighting for"
This is a general statement about "peace".
"A peace that is worth fighting for"
This statement suggests that the speaker has a specific view of what he considers peace. He is saying, "Of all the different types or interpretations of peace there are, I think this one is worth fighting for.
In the case