On the night He was betrayed, Jesus told His disciples that the cup poured out for them was the new covenant in His blood (Luke 22:20). It is the sign of the promise revealed in Ezekiel 36 and Jeremiah 31. The Lord committed to Israel that He would cleanse their sins, take away their hearts of stone, give them hearts of flesh, and cause each of them to know Him. This covenant stands out because it depends wholly on the Lord. As it’s been observed, no man can give himself a heart transplant.
Not only is this promise unconditional, it is also as reliable as the sunrise. Jeremiah explains what would need to happen before this promise could fail.
“Behold, the days are coming, declares the LORD, when I will make a new covenant with the house of Israel and the house of Judah, not like the covenant that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt, my covenant that they broke, though I was their husband, declares the LORD. For this is the covenant that I will make with the house of Israel after those days, declares the LORD: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. And no longer shall each one teach his neighbor and each his brother, saying, ‘Know the LORD,’ for they shall all know me, from the least of them to the greatest, declares the LORD. For I will forgive their iniquity, and I will remember their sin no more.”
Thus says the LORD,
who gives the sun for light by day
and the fixed order of the moon and the stars for light by night,
who stirs up the sea so that its waves roar—
the LORD of hosts is his name:
“If this fixed order departs
from before me, declares the LORD,
then shall the offspring of Israel cease
from being a nation before me forever.” (Jeremiah 31:31–36)
God established the light and seasons of the sun to teach us about His strength and faithfulness. Through these God also shows His joy. As Chesterton speculated in his book Orthodoxy, “It is possible that God says every morning, ‘Do it again’ to the sun.” He does not get tired of calling the sun into place, and He does not tire of keeping His promises.
We Gentiles partake as the overflow of the new covenant life. There is a season when God is grafting in those who had no promise to receive the salvation, and even this is part of God’s plan to finally save Israel (Romans 11:25-27).
As we eat and drink communion week by week, as we cross off days on the calendar until the Son comes, as we take it for granted when our weather apps say the sun will come up tomorrow, then we have reason to trust God in all His good words to us.