This text opens what has sometimes been called Third Isaiah--chapters 56-66, which seem to reflect the difficult situation back in Jerusalem after the exiles have returned to Jerusalem from Babylon. The chapters contain promises similar to those of Second Isaiah and words of judgment similar to those of the preexilic prophets.
This opening passage is one of the most inclusive promises in Isaiah and in the entire Bible. The place of foreigners among the people of Israel had been ambiguous--according to the Torah, aliens were to be welcomed and protected (Leviticus 19:34), but other laws required separation between Israelites and outsiders (Ezra 9:1-4). In this text, foreigners who "join themselves to the LORD" (that is, proselytes) will be accepted as full members of God's people. More strikingly, this applies to eunuchs as well. Eunuchs were excluded from temple worship by Torah itself (Deuteronomy 23:1-3; Leviticus 21:18-20), not for moral or ethnic reasons but because they were understood to be "blemished," excluded by the purity laws in the same way that blemished lambs were not acceptable as sacrifices. This is a ritual exclusion that did not regard the "blemished" as morally or socially inferior, but there were real social and religious consequences. According to Leviticus, they could not serve as priests; for Deuteronomy, they could not be admitted to the assembly of God's people at all.
But now, says the Lord (through the prophet), all that is changed. Foreigners and eunuchs are welcomed in the same way as anyone else--that is, those who keep the sabbath and hold fast the covenant. Sabbath-keeping had taken on even greater importance during the exile because it was a religious observance and a sign of the covenant that people could do within the family even when there was no temple for sacrifice and festival worship.
The secret to the openness expressed in these verses seems to come at the end: God will gather these "outcast" (foreigners and eunuchs) to the "outcasts of Israel" already gathered. None are members of God's people by right; all are outcasts, brought in by grace (Deuteronomy 7:7-8). Those who know themselves to be gathered outcasts will more easily welcome other outcasts into their midst.
This text finds one fulfillment in Acts 8:26-40, where Philip is sent to proclaim the good news to an Ethiopian eunuch who is reading Isaiah in his chariot. The man is an example in his own person of both the foreigners and the eunuchs who are welcomed here in this Isaiah text. "What is to prevent me from being baptized?" asks the eunuch (Acts 8:29). One would have to answer, certainly not Isaiah 56!
56Thus says the Lord:
Maintain justice, and do what is right,
for soon my salvation will come,
and my deliverance be revealed.
2 Happy is the mortal who does this,
the one who holds it fast,
who keeps the sabbath, not profaning it,
and refrains from doing any evil.
3 Do not let the foreigner joined to the Lord say,
The Lord will surely separate me from his people;
and do not let the eunuch say,
I am just a dry tree.
4 For thus says the Lord:
To the eunuchs who keep my sabbaths,
who choose the things that please me
and hold fast my covenant,
5 I will give, in my house and within my walls,
a monument and a name
better than sons and daughters;
I will give them an everlasting name
that shall not be cut off.
6 And the foreigners who join themselves to the Lord,
to minister to him, to love the name of the Lord,
and to be his servants,
all who keep the sabbath, and do not profane it,
and hold fast my covenant
7 these I will bring to my holy mountain,
and make them joyful in my house of prayer;
their burnt-offerings and their sacrifices
will be accepted on my altar;
for my house shall be called a house of prayer
for all peoples.
8 Thus says the Lord God,
who gathers the outcasts of Israel,
I will gather others to them
besides those already gathered.*
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org