Someone has posited that Isaiah 56:6-7 says we must follow the Law. Let’s take a look.
To look at Isaiah 56:6-7, we must look at it in context, so lets look at Isaiah 56:1-7
1 Thus says the LORD, “Preserve justice and do righteousness, For My salvation is about to come And My righteousness to be revealed. 2 ”How blessed is the man who does this, And the son of man who takes hold of it; Who keeps from profaning the sabbath, And keeps his hand from doing any evil.” 3 Let not the foreigner * who has joined himself to the LORD say, “The LORD will surely separate me from His people.” Nor let the eunuch say, ”Behold, I am a dry tree.” 4 For thus says the LORD, “To the eunuchs who keep My sabbaths, And choose what pleases Me, And hold fast My covenant, 5 To them I will give in My house and within My walls a memorial, And a name better than that of sons and daughters ; I will give them an everlasting name which will not be cut off. 6 ”Also the foreigners * who join themselves to the LORD, To minister to Him, and to love the name of the LORD, To be His servants, every one who keeps from profaning the sabbath And holds fast My covenant ; 7Even those I will bring to My holy mountain And make them joyful in My house of prayer. Their burnt offerings and their sacrifices will be acceptable on My altar ; For My house will becalled a house of prayer for all the peoples.”
We see in Isaiah 56:1 that God is saying His salvation is about to come and His righteousness to be revealed – this is speaking of Christ. God’s salvation will be available to all people. The foreigner who trusts in Christ will no longer be separated from the Jew. The Eunuch who can have no children will not longer be separate from the rest of the God-fearing people. The description is one who chooses to please God and holds fast to His covenant. We can tell from verse 7 that this is a time of change – the burnt offerings and sacrifices will be acceptable on God’s altar. This can not be speaking of a time after the New Covenant was firmly established, because we know Christ is our sacrifice, and that believers in Christ are to offer up spiritual sacrifices, and sacrifices of praise: giving thanks, and sacrifices of doing good and sharing.
1 Peter 2:5
We know from Hebrews 10:8 that God did not desire burnt offerings and sacrifices for sin, but Christ did away with the Old Covenant and the Law.
8 After saying above, “Sacrifices and offerings and whole burnt offerings and sacrifices for sin You have not desired, nor have You taken pleasure in them” (which are offered according to the Law), 9 then He said, “Behold, I have come to do Your will.” He takes away the first in order to establish the second. 10 By this will we have been sanctified through the offering of the body of Jesus Christ once for all.
11 Every priest stands daily ministering and offering time after time the same sacrifices, which can never take away sins; 12 but He, having offered one sacrifice for sins for all time, sat down at the right hand of God, 13 waiting from that time onward until His enemies be made a footstool for His feet. 14 For by one offering He has perfected for all time those who are sanctified. 15 And the Holy Spirit also testifies to us; for after saying,
16 “This is the covenant that I will make with them
After those days, says the Lord:
I will put My laws upon their heart,
And on their mind I will write them,”
He then says,
17 “And their sins and their lawless deeds
I will remember no more.”
18 Now where there is forgiveness of these things, there is no longer any offering for sin.
Not only did God do away with sacrifices and offerings, Christ sacrificed himself once for all, and instituted the New Covenant, where He wrote His laws upon the hearts and minds of those who trust him, and forgives the sins of those who trust Him. And where there is forgiveness of sin, there is no longer any offering for sin. Since our sins have been forgiven, this has to speak of the time right before and after Christ was crucified.
26 But an angel of the Lord spoke to Philip saying, “Get up and go south to the road that descends from Jerusalem to Gaza.” (This is a desert road.) 27 So he got up and went; and there was an Ethiopian eunuch, a court official of Candace, queen of the Ethiopians, who was in charge of all her treasure; and he had come to Jerusalem to worship, 28 and he was returning and sitting in his chariot, and was reading the prophet Isaiah. 29 Then the Spirit said to Philip, “Go up and join this chariot.” 30 Philip ran up and heard him reading Isaiah the prophet, and said, “Do you understand what you are reading?” 31 And he said, “Well, how could I, unless someone guides me?” And he invited Philip to come up and sit with him. 32 Now the passage of Scripture which he was reading was this:
“He was led as a sheep to slaughter;
And as a lamb before its shearer is silent,
So He does not open His mouth.
33 “In humiliation His judgment was taken away;
Who will relate His generation?
For His life is removed from the earth.”
34 The eunuch answered Philip and said, “Please tell me, of whom does the prophet say this? Of himself or of someone else?” 35 Then Philip opened his mouth, and beginning from this Scripture he preached Jesus to him. 36 As they went along the road they came to some water; and the eunuch *said, “Look! Water! What prevents me from being baptized?” 37 [And Philip said, “If you believe with all your heart, you may.” And he answered and said, “I believe that Jesus Christ is the Son of God.”] 38 And he ordered the chariot to stop; and they both went down into the water, Philip as well as the eunuch, and he baptized him. 39 When they came up out of the water, the Spirit of the Lord snatched Philip away; and the eunuch no longer saw him, but went on his way rejoicing.
So no, Isaiah 56:6-7 does not show the need for Christians following the Law. It is part of a passage which shows someone who loved God and was a foreigner and an eunuch and offered sacrifices and burnt offerings and honored the Sabbath, yet whose sins were forgiven when He accepted what Christ had done.