Here's some follow-up discussion I'm having with someone about Sunday as Sabbath.
These thoughts are me trying to work out a defined position myself. Feel free correct any mis-steps you see here...
First, I miscommunicated if you think my position is that we no longer have, or observe, the Sabbath.
We do. But it is a different sort of Sabbath, focused on celebrating the resurrection, with the revealed purpose of entering rest in Christ. Less emphasis on (not abolishment of) no work commands. I don't think this changes the Isaiah passage (58:13-14) much at all.
One way to answer your question is with the Heidelberg catechism's Q&A 103: (Heidelberg and many reformers on the European continent didn't say the sabbath was "moved," nor did they say it was "abolished.")
Q. What is God's will for you
in the fourth commandment?
that the gospel ministry and education for it be maintained,^1
and that, especially on the festive day of rest,
I regularly attend the assembly of God's people^2
to learn what God's Word teaches,^3
to participate in the sacraments,^4
to pray to God publicly,^5
and to bring Christian offerings for the poor.^6
that every day of my life
I rest from my evil ways,
let the Lord work in me through his Spirit,
and so begin already in this life
the eternal Sabbath.^7
^1 Deut. 6:4-9, 20-25; 1 Cor. 9:13-14; 2 Tim. 2:2; 3:13-17; Tit. 1:5
^2 Deut. 12:5-12; Ps. 40:9-10; 68:26; Acts 2:42-47; Heb. 10:23-25
^3 Rom. 10:14-17; 1 Cor. 14:31-32; 1 Tim. 4:13
^4 1 Cor. 11:23-25
^5 Col. 3:16; 1 Tim. 2:1
^6 Ps. 50:14; 1 Cor. 16:2; 2 Cor. 8 & 9
^7 Isa. 66:23; Heb. 4:9-11
There is a spectrum of Sabbath views from the strongly "Sabbatarian" that agrees completely with Westminster, to the view of Calvin, and other views in the middle:
Strong sabbatarian: the Sabbath has moved from Saturday to Sunday. It is a day for no activity but worship, piety, necessity and mercy. No recreation for the self is allowed. Isa 58 forbids it.
Calvin (hoping I'm not mischaracterizing): the Sabbath is abolished as part of the ceremonial law. It is right for the church to all worship on one day, and the NT church chose Sunday, the Lord's Day. It also makes sense to retain the 1 in 7 principle of rest from work, but this is no longer morally binding as it was in the OT.
Middle position (mine, I think): we have a new Sabbath, as we have a new creation order in Christ. Most of the old sabbath definitions still apply, though not as rigidly, as the center is now clear: rest in Christ. The center is no longer refraining from work, but worship (focus on Christ, our rest) and loving the saints. Recreation for self is allowed; refraining from work is still a moral command, but exceptions are allowed, given vocational necessity.