From the very beginning, the Creator ordained that mankind be busy with His Word and with the forms of worship established by Him. On the Sabbath Day, Adam "would have taught his children; through public preaching he would have bestowed honor on God with the praises which He deserved; and through reflection on the works of God he would have incited himself and others to expressions of thanks" (Luther's Works 1:82).As Adam worshiped, it was God's design that the tree of the knowledge of good and evil be the designated place where Adam, and his house, would come to worship God. At this tree, Adam "was to yield to God the obedience he owed, give recognition to the Word and will of God, give thanks to God, and call upon God for aid against temptation" (LW 1:95).
God's command concerning the tree was to be "an outward form of worship and an outward work of obedience toward God" (LW 1:109). It was God's intention that this command should provide man with an opportunity for obedience and outward worship, and that this tree should be a sort of sign by which man would give evidence that he was obeying God (LW 1:154). This tree was not deadly by nature but became so only by the Word of God and man's disobedience.
As a result of Adam's sin, unregenerate man is filled with fear and he quickly hides from a punishing God (LW 1:170). In loving response to man's sin and rebellion God, in His mercy, enveloped Himself in a gentle breeze so that He might reveal Himself to Adam under a cover and bring to Adam and Eve a fatherly reprimand.
It was a great comfort for Adam that, after he had lost Paradise and the tree of life, God gave him another sign of grace, namely, the sacrifices. In this sign Adam could know that he had not been cast off by God but that he was still the object of God's concern and regard (LW 1:249).
At that time, men began to call upon the name of the Lord (Genesis 4:26). Shem, Seth, and Enos exhorted their descendants to wait for their redemption and to believe the promise concerning the woman's Seed. As evidenced in the lives of the patriarchs, the true church trusts in God's mercy and hopes in the promised Christ for "all ages had the knowledge of the Blessed Seed" (LW 2:164).
Alongside the Gospel, the sacrifices provided an outward and visible sign of His grace. This sign reminded men of His mercy and kindness and provided the proper form of worship in which He could be found (LW 1:248). Thus "Abel and Cain had been accustomed by their father to sacrifice, which at that time was the proper form for the worship of God; and they continued to offer sacrifice. In the same manner Shem had meetings, sermons, forms of worship, sacrifices, and other ceremonies, which continued in existence up to the time of Abraham" (LW 2:197).
It is in the sacrifices of Abel and Cain, believed Luther, that we begin to differentiate between the true and the false church. Cain appears to be saintly but he is wicked and does not believe the divine promise. In Cain's contempt for the rejection of the promise concerning the Blessed Seed, he left the true church to form a special church without God's command. Abel, on the other hand, is godly and believes solely in the mercy of Christ. "Abel did not rely on his own worthiness, his sacrifices, or his work, but on the plain promise which had been given about the woman's Seed" (LW 1:259).
Moreover, just as Abel and Cain formed two churches, so also Ham, after the flood, left the godly church of his father Noah and established a false and lying church. It is Ham's descendants, especially his grandson Nimrod, who seek to build a name for themselves and persecute the true church spiritually, by means of false doctrine and ungodly forms of worship, and physically, by means of the sword and tyranny (LW 2:214). Yet God has always counteracted the false church with a people who would cling to His Word and the forms of worship instituted by Him. They would be the "guardian of religion and of sound doctrine in the world lest everything degenerate into ungodliness and there be no knowledge of God among men" (LW 2:228-229).
Thus later on, when Abraham was nearly swallowed up by the false church of Nimrod and its Babylonian religion, God called him out through the ministry of Shem and directed him to separate from the ungodly race and seek a new dwelling place. Abraham is seized through the Word and formed into a new being and into a patriarch. Of himself, Abraham is nothing but an idolater but through His mercy, "he is freed from sin, death and damnation through Christ, the Blessed Seed" (LW 2:247).
When Jacob was near death, as he was blessing his sons, he foresaw that his descendants would continue to form two churches. The true church would be saved because of faith in the promise concerning the Savior who was to descend from Jacob's flesh. The false church would consist of carnal Israelites who would boast that they were the seed of Abraham but have neither His Word nor the signs ordained by Him (LW 8:217). Instead of clinging to the Word and His signs of grace, these carnal Israelites began to run after the desires of their hearts, forgetting His commandments and ceremonies and, after despising the tabernacle and temple, they brought their sacrifices under trees and groves and even sacrificed their own children (LW 1:249). Instead of taking hold of Him in the sign, everyone devised his own way of worshiping God and followed it to his own certain destruction (LW 3:108).
In contrast, there is nothing more precious in the world than the church where His voice is heard and where God is worshiped with true forms of worship, that is, faith, invocation, patience and obedience. Therefore, the true church is made up of those who have the promise concerning the Blessed Seed and believe it (LW 4:31). The false church, on the other hand, rejects the promises of God and concerns itself with things that He has not commanded nor promised.