I would suggest that you have a misconception of grace. Grace is unmerited favor but in order to be saved by grace we must obey God. God’s grace shows us the path of salvation, but we must walk the path. Jesus's work is finished, but that's where ours begins.
Couple of examples, Noah received grace but in order to save himself and his family he had to do obey.
Gen. 6:7 And the Lord said, I will destroy man whom I have created from the face of the earth; both man, and beast, and the creeping thing, and the fowls of the air; for it repenteth me that I have made them. 8 But Noah found grace in the eyes of the Lord.
God’s grace warned Noah of the pending destruction and gave him a way of “salvation”.
Heb. 11:7 By faith Noah, being warned of God of things not seen as yet, moved with fear, prepared an ark to the saving of his house;
Grace through faith.
Another example, the Passover which is a shadow of how Christ’s blood saves us.
21 Then Moses called for all the elders of Israel, and said unto them, Draw out and take you a lamb according to your families, and kill the passover. 22 And ye shall take a bunch of hyssop, and dip it in the blood that is in the basin, and strike the lintel and the two side posts with the blood that is in the basin; and none of you shall go out at the door of his house until the morning. 23 For the Lord will pass through to smite the Egyptians; and when he seeth the blood upon the lintel, and on the two side posts, the Lord will pass over the door, and will not suffer the destroyer to come in unto your houses to smite you.
Yes, Jesus sacrifice was sufficient to save our souls, but how is his blood applied to each individual? In our case, the lamb offered himself and his blood is in the basin waiting to be applied. Once he offered himself, how does he tell us to be saved, effectively applying his blood to the lintel and side posts?
Mark 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Grace teaches us the path of salvation, but we must walk it by obeying it’s instructions. For conversion and how to live.
Titus 2:11 For the grace of God that bringeth salvation hath appeared to all men, 12 Teaching us that, denying ungodliness and worldly lusts, we should live soberly, righteously, and godly, in this present world;
What happens to those who do not obey the gospel.
8 In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ:
This is my current understanding of grace.