Either we are saved by grace or we are saved by works. Either we deserve our salvation or it is undeserved mercy. It cannot be both. Paul was pretty clear:
Rom 11:6 And if by grace, then [is it] no more of works: otherwise grace is no more grace. But if [it be] of works, then is it no more grace: otherwise work is no more work.
So...if we are saved by grace, we STAY saved by grace because we haven't received Heaven yet. To say we are saved by grace but must work to stay saved, is a contradiction. It is a "strawman" to to call this "easy-believism" or to say it gives people a license to sin. Nothing is further from the truth and totally discounts the work of the Holy Spirit in our lives and the discipline of our Heavenly Father.
Bzzzzt. A common error.
We are saved by faith and works.
It's not "either/or". Both are required if you stick with Scripture.
Rom 11:6
A good dissertation to the Jews that works of the law, or the old covenant, are of no avail.
To say we are saved by grace but must work to stay saved, is a contradiction.
It's not a contradicition in Scripture. Just understand that in the Letter of James it is not talking about the old covenant, but the new, when discussing "works".