Mr. Joo-cheol Kim of the Church of God cites Isaiah 55 to argue that the eternal covenant given to David is the Passover because it testifies that David represents Jesus and that the new covenant established by Jesus is the Passover. However, Mr. Kim's argument is ignorant and shallow, not knowing the basics of the Bible.

[Isaiah 55:3] Give ear and come to me; hear me, that your soul may live. I will make an everlasting covenant with you, my faithful love promised to David.

Through Isaiah, God said he would make an everlasting covenant with his people, and that covenant would be the same as the one he gave to David. So in order to know what an everlasting covenant is, we must first know what covenant God gave to David.  When God chose David, he made him king over Israel and gave him great wealth and power. Furthermore, he promised that the wealth, power, and kingship that he gave to David would be given not only to David, but to his descendants and their descendants' descendants forever.

[2 Samuel 7:8~16]  "Now then, tell my servant David, 'This is what the LORD Almighty says: I took you from the pasture and from following the flock to be ruler over my people Israel. I have been with you wherever you have gone, and I have cut off all your enemies from before you. Now I will make your name great, like the names of the greatest men of the earth. And I will provide a place for my people Israel and will plant them so that they can have a home of their own and no longer be disturbed. Wicked people will not oppress them anymore, as they did at the beginning and have done ever since the time I appointed leaders over my people Israel. I will also give you rest from all your enemies. " 'The LORD declares to you that the LORD himself will establish a house for you: When your days are over and you rest with your fathers, I will raise up your offspring to succeed you, who will come from your own body, and I will establish his kingdom. He is the one who will build a house for my Name, and I will establish the throne of his kingdom forever. I will be his father, and he will be my son. When he does wrong, I will punish him with the rod of men, with floggings inflicted by men. But my love will never be taken away from him, as I took it away from Saul, whom I removed from before you. Your house and your kingdom will endure forever before me ; your throne will be established forever.' "

So the everlasting covenant granted to David is a promise that not only David, but also his descendants, would be king over Israel and reign forever. Eventually, this promise was passed down to Jesus, who came as a descendant of David, and Jesus was granted eternal kingship. However, while David was established as the physical king of Israel, Jesus was established as the spiritual king of Israel. Jesus was anointed as the king of Israel because he came by the Holy Spirit. Since those who receive God's Holy Spirit are anointed as kingly priests, all those who receive the Holy Spirit become descendants of David, and the kingship is passed down to them, which is the eternal covenant promised by God. However, the Church of God's Kim Joo-cheol does not know these secrets, so he makes the ignorant claim that the Passover is the eternal covenant.

[ Isaiah 59:20~21] "The Redeemer will come to Zion, to those in Jacob who repent of their sins," declares the LORD. "As for me, this is my covenant with them," says the LORD. "My Spirit, who is on you, and my words that I have put in your mouth will not depart from your mouth, or from the mouths of your children, or from the mouths of their descendants from this time on and forever," says the LORD.