The fact is that the idea of salvation via grace through faith can be used by leaders and church members alike to foster cheap grace and easy salvation where all that is required is a mouthed declaration of faith and bingo!...you are saved. It doesn't matter if you really believe it or not or do anything about it , you just have to say the words and click your heels and heaven is yours.
Now , the fact that this does happen is often used by the anti - grace brigade as a get out jail free card whenever they need an argument against salvation via grace.
Have they never heard of throwing the baby out with the bath water?
The fact that grace can be abused says nothing about whether the concept of salvation via grace/faith is false or not. Anymore than the fact that wars can start over national frictions proves that having pride in one's country is wrong.
Why do the anti-grace brigade always talk as if we don't realise that grace can be abused? Duh? We do know this you know.
There are of course exremes of abuse at the other end of the spectrum , but these extremes are neither here nor there. What men do with any idea doesn't always tell us whether that idea is false or not.