In Isaiah 56, God spoke through Isaiah concerning the salvation of foreigners, those who were not of Abraham's seed.
God said to uphold justice and righteousness, because soon His salvation would come. God was speaking of the coming Messiah, and said that soon His righteousness would be revealed.
Through Isaiah, God said that the man who lives in righteousness is blessed. Those who keep the Sabbath and do not profane it, and those who keep their hands from doing any evil.
This was not only to the seed of Abraham. God said not to let the foreigners who have joined themselves to the Lord think they should be dealt with separately from His people; all who joined themselves to the One True God were His people.
God said not to place their faith in their bloodlines. He reminded the people of the eunuchs, and told them not to mourn. They should not tell themselves they are a "dry tree," for God would bless them. The eunuchs who uphold the things that please God would be given a house in His kingdom with a monument and a name that was better than sons and daughters. They would be given an everlasting name that would not be cut off.
Those that were not the seed of Abraham and joined themselves to the Lord to minister to Him, and love the Name of the Lord would be given joy in the House of the Lord on His Holy Mountain. Because they kept the Sabbath and did not profane it, and because they held fast to His covenant, their sacrifices and burnt offerings would be accepted on God's altar.
God said that His house would be called a House of Prayer for all peoples. The Lord God declared that He would gather even more together, from the outcasts of Israel and beyond.
As Christians, we should ask ourselves: Do we place value in our bloodlines, thinking that because our fathers were saved that we are too? Do we think that because of our earthly heritage that we are given a special place in God's Kingdom? Do we think that there is also an evil bloodline that God will destroy, like the children of Israel thought in Isaiah's day? Have we joined ourselves to an earthly bloodline, or have we joined ourselves to a heavenly bloodline of the redeemed? Do we seek out our own salvation with fear and trembling to become a member of that bloodline? Do we separate ourselves from other Christians, or do we join together with all of God's children to give Him praise and worship?