Was righteous Abel saved by grace or was it by something he did?
Where God says "do this" - faith believes God knows what's what and does what is commanded.
And where God says "it is finished - believe" - faith believes God knows what's what and does what is commanded.
Be it do, or believe it is done, the issue in both is...faith.
Be it circumcision, when doing that in faith, had been the issue...then...or uncircumcision in faith...now.
In short, Dispensationalism.
Luke 12:42 And the Lord said, Who then is that faithful and wise steward, whom his lord shall make ruler over his household, to give them their portion of meat in due season? 12:43 Blessed is that servant, whom his lord when he cometh shall find so doing. 12:44 Of a truth I say unto you, that he will make him ruler over all that he hath.
1 Corinthians 4:2 Moreover it is required in stewards, that a man be found faithful.
1 Corinthians 9:17 For if I do this thing willingly, I have a reward: but if against my will, a dispensation of the gospel is committed unto me.