God had barely given the Law to Moses when He ordered that it be put in a coffin. That’s right — a coffin. The reason for this is that the Mosaic covenant clearly stipulated:
“Now therefore, IF YE WILL OBEY MY VOICE INDEED, and keep My covenant, THEN ye shall be a peculiar treasure unto Me above all people, for all the earth is Mine” (Ex. 19:5).
Israel, of course, did not obey God’s voice indeed, but broke the Law before Moses even got down from Sinai. It was because of this that God, in grace, commanded: “And they shall make an ark…” (Ex. 25:10). This word “ark” is rendered “coffin” in the last verse of Genesis and that is its simple meaning. But why did God order a coffin as the very first article of furniture for the tabernacle? The answer is: To put the Law in. Read it for yourself:
“And thou shalt put into the COFFIN the testimony [the Law] which I shall give thee… and thou shalt put the MERCY SEAT above upon the coffin…” (Ex. 25:16,21).
If God had not put the covenant of the Law in a coffin and met His people from a “mercy seat” none of them ever would have been saved.
This Old Testament type has a lesson for us today, for if God dealt with us according to our works none of us would ever be saved, but “Christ died for our sins,” meeting for us the just demands of a broken Law, so that we might be saved by grace through faith in His redemptive work.
Col. 2:14 says concerning this “handwriting of decrees, that was against us,” that our Lord, in death, “took it out of the way, nailing it to His cross,” and Rom. 7:6 explains:
“But now we are DELIVERED FROM THE LAW, that being DEAD wherein we were held; THAT WE SHOULD SERVE IN NEWNESS OF SPIRIT, and not in the oldness of the letter.”
Thus believers in Christ are saved “by grace… through faith… not of works” but “unto good works, which God hath before ordained that we should walk in them” (Eph. 2:8-10). source