The Mosaic covenant and Law promised blessings for obedience and curses for disobedience (conditional), but one's individual Salvation is always based on grace, thru faith - any then lawful observance of what God commands is what Believers bother to do.liable to be saved or destroyed based on their own individual righteousness or wickedness.
As Believers, they would already be saved.
The Saved are saved in spite of their not deserving it.
Israel's national salvation is also not their doing, it's completely God's doing based on what He promised and His faithfulness.
The Abrahamic covenant is unconditional.