I
disagree with you that grace necessarily requires a response of the heart. Grace can be present without any kind of heart response.
Sometimes the grace of God does expect and obtain a response from the one receiving it and sometimes not.
In the case of the grace of God which issues in salvation - obviously it does. (Obviously to me at least.)
In the case of other kinds of grace (common grace for example) - not so much.
Having said that - I would like to correct a mistake that I made before.
You were right to say that the word grace does not mean "unmerited favor". Much grace may indeed be unmerited (as with election for instance IMO). But in other cases it may be actually merited - grace in the scriptures that is based on humbleness or good stewardship for example.
But - even though grace
MAY be unmerited in many cases -
unmerited favor would not be a proper definition of grace just because of that.
In like manner - just because grace
MAY be merited in many cases -
merited favor would not be a proper definition of grace just because of that.
After some consideration of the matter - I stand corrected. I have often used "unmerited favor" as a
universal definition of the word grace. I will be more careful in the future. It is not a good "definition".
I doubt that the widespread use of that definition for all grace as used in scripture is to be necessarily linked with Free Grace theology as you assert.
But I do not doubt that the widespread knowledge and use of the Ephesians passage (where grace that issues in salvation is to be seen as "unmerited") is the main reason that many people have wrongly used unmerited favor as a definition of grace. (Something along the lines of what you pointed out to me about widespread use wrongly becoming the norm for definitions over time.)
A more proper definition of the actual word used in scripture would be something like good will, loving-kindness or favor.
Again - the loving kindness and favor of God that issues in salvation is definitely to be considered as unmerited as I have said.
But I (no less than others it seems) need to be careful when using commonly accepted definitions as authoritative when dealing with the Greek, Aramaic or Hebrew words used in the scriptures.
In the recent past here in this thread - I took a person to task for blindly using the opinion of "Strong's" when defining regeneration. In that particular case Strong's was making some assumptions in it's choice of definitions. As a result, it was functioning more like a commentary than just a pure Greek authority.
It seems obvious now that I do the same kind of thing occasionally if I'm not careful. Many sources for definitions go a little far afield in choosing how to define certain Greek or Hebrew words.
I plan to be a lot more careful in the future.
See - you can teach an old dog new tricks.