The term "merit," in Catholic theology, means "to have a claim on a reward," not necessarily "to deserve a reward in strict justice".
So, yes, in some contexts we do "merit grace," even if all we do to merit grace is ask for it.
You indicate that you understand “Catholic theology”. The paragraphs that I wrote on “merit” were taken directly from the Catechism of the CC (2006-2011).
Each independent protestant group within the various dominations (tens of thousands!) interprets Sacred Scripture in their own way. In a rather confusing world filled with innumerable opinions, we Catholics should be grateful to Jesus for leaving us the living “ROCK” until the end of time (Mt 16:18)! It takes humility to submit to the Church that Jesus left us, rather than each person making up his own mind about truth, morals, etc. Jesus knew there would be this confusion and thousands of opinions about these things even though there is one Bible, one God, and one Jesus Christ! That is why He left us the Rock, the living Pope!
The more one sins and the less one prays, the more one becomes blind to reality and to the truth. “God shall send them strong delusion, that they should believe a lie: that they all might be damned who believed not the truth, but had pleasure in unrighteousness.” (2Thess 2:11-12). Does this not also include what Pope Benedict XVI was referring to as the “tyranny of relativism”? Have not the vast majority of people and Christians (including Catholics) yielded to the most fundamental and continual temptation of Satan? “But the serpent said to the woman, “You will not die. For God knows that when you eat of it your eyes will be opened, and you will be like God, knowing good and evil” “(Gen 3:4-5). Today so many have put themselves in the place of God by deciding by themselves that abortion and so many other sins against the 10 commandments and against all the revelation of God is OK! But where do such people go after they die if they do not repent beforehand? To the heaven that they created? Or have they convinced themselves, being little gods, that heaven does not exist and so they can live as they wish here on earth with no eternal consequences? Who decides what is right and wrong, good and evil, truth and reality? The puppets of Satan, the modern philosophers, would make us to believe that each person becomes a god! For a believer in God-Love, René Descartes’ famous supposition “I think therefore I am” should read “I love therefore I am”! But true love is lived as Jesus did on the cross, sacrificial altruistic love, in our daily lives!