Israel couldn’t do all they can do
Ezekiel 20: 20-22
20 And hallow my sabbaths; and they shall be a sign between me and you, that ye may know that I am the Lord your God.
21 Notwithstanding the children rebelled against me: they walked not in my statutes, neither kept my judgments to do them, which if a man do, he shall even live in them; they polluted my sabbaths: then I said, I would pour out my fury upon them, to accomplish my anger against them in the wilderness.
22 Nevertheless I withdrew mine hand, and wrought for my name's sake, that it should not be polluted in the sight of the heathen, in whose sight I brought them forth.
Do you see what God has just said? in other words, "But I withheld my hand and acted for the sake of my name, that it should not be profaned in the sight of the nations, in whose sight I had brought them out."
Even God's holy nation couldn't get it right, reflect that notion back us the rest of us, so how can we be expected to?
The short answer is, He never expected us to.
God is not bound by our ability to keep covenants, baptising for our dead relatives, or becoming worthy for a temple recommend. God is speaking about being bound by his own holy nature. HIS name sake.
Salvation is granted wholly and solely at the provision, direction and grace of God, it is 100% our saviour's purchase on the cross and 0% our ability. But He is a gentleman, you need only to accept the keys to the kingdom before it becomes yours.