D. G. Hart and John R. Muether in With Reverence and Awe: Returning to the Basics of Reformed Worship (Phillipsburg, NJ: Presbyterian and Reformed, 2002) say,
“Manna in the wilderness was a peculiar experience for the Israelites. It was unlike anything in their Egyptian diet. At times they were given to grumbling, for it was less appetizing than Egyptian fare. So too ought we to see something strange about the spiritual diet God provides for us. To change the metaphor, some have compared worship to the process of mastering a foreign tongue. ‘We must learn Christianity,’ writes William Willimon, ‘even as we learn a foreign language’ [Peculiar Speech: Preaching to the Baptized (Grand Rapids: Eerdmans, 1992), 114]. Peter Leithart suggests that ‘worship is a language class, where the Church is trained to speak Christian’ [“Cult and Culture,” First Things 29 (Jan 1993): 7]. One learns a language by mastering difficult rules through repetition. We have no hope of speaking any language fluently if its conjugations and declensions change every week. . . .
“The church that properly worships will be peculiar to the world. Its ways will seem at odd and irrelevant, and its language will sound strange. In a word, God’s holy pilgrims will appear to be sectarians. This is because the church, saved by God in order to worship him, sees itself in light of God’s purposes, not the world’s expectations. God has elected us by his good pleasure, delivered us from the bondage of sin, and set us apart from the world, where, like the Israelites in exile, we are to sing the Lord’s song in a foreign land” (59-60).
I think the authors are right in identifying the church as pilgrims. God has, after all, “delivered us from the domain of darkness and transferred us to the kingdom of his beloved Son, in whom we have redemption, the forgiveness of sins” (Col 1:13-14, ESV). Thus we can identify with the spirit and faith of the patriarchs when it says of them in Hebrews 11:13-16,
These all died in faith, not having received the things promised, but having seen them and greeted them from afar, and having acknowledged that they were strangers and exiles on the earth. For people who speak thus make it clear that they are seeking a homeland. If they had been thinking of that land from which they had gone out, they would have had opportunity to return. But as it is, they desire a better country, that is, a heavenly one. Therefore God is not ashamed to be called their God, for he has prepared for them a city.
Correctly viewing the church as an outpost of pilgrims frees the church to pursue wholly after the Lord in worship, without giving a backward glance to what the world may think of it. We can freely go to the Scriptures and let them prescribe our worship, without fearing whether or not it will be “relevant” to someone who does not even know what true Relevance is. We are freed to worship God with boldness and conviction, not hedging our culture and teaching around the dictates of the present age. Understanding the church in this way frees us from having to entertain or amuse, from feeling like we have to compete with the pagan liturgy of Saturday night. Understanding the church as an outpost of pilgrims for the Kingdom frees us to worship the true and living God as He is.