"Make thee an ark of gopher wood; rooms shalt thou make in the ark, and shalt pitch it within and without with pitch" (Genesis 6:14).
It may be surprising to learn that God's instructions to Noah concerning the Ark's design contain the first reference in the Bible to the great doctrine of atonement. The Hebrew word used here for pitch (kaphar) is the same word translated "atonement" in many other places in the Old Testament.
While the New Testament word "atonement" implies reconciliation, the Old Testament "atonement" was merely a covering (with many applications). As the pitch was to make the Ark watertight, keeping the judgment waters of the Flood from reaching those inside, so, on the sacrificial altar, "it is the blood that maketh an atonement for the soul" (Leviticus 17:11), keeping the fires of God's wrath away from the sinner for whom the sacrifice was substituted and slain. The pitch was a covering for the Ark, and the blood was a covering for the soul, the first assuring physical deliverance; the second, spiritual salvation.
However, not even the shed blood on the altar could really produce salvation. It could assure it through faith in God's promises on the part of the sinner who offered it, but "the blood of bulls and of goats" could never "take away sins" (Hebrews 10:4).
Both the covering pitch and animal blood were mere symbols of the substituting death of Jesus Christ, "Whom God hath set forth to be a propitiation through faith in His blood, to declare His righteousness for the remission of sins that are past, through the forbearance of God" (Romans 3:25). Through faith in Christ, our sins are "covered" under the blood, forgiven by God, and replaced by His own perfect righteousness, by all of which we become finally and fully reconciled to God. HMM