The church: Locke and the Heidelberg Catechism

North American denominationalism seems to owe much to John Locke's definition of church in his Letter Concerning Toleration:

A church, then, I take to be a voluntary society of men, joining themselves together of their own accord in order to the public worshipping of God in such manner as they judge acceptable to Him, and effectual to the salvation of their souls.

I say it is a free and voluntary society. Nobody is born a member of any church; otherwise the religion of parents would descend unto children by the same right of inheritance as their temporal estates, and everyone would hold his faith by the same tenure he does his lands, than which nothing can be imagined more absurd. Thus, therefore, that matter stands. No man by nature is bound unto any particular church or sect, but everyone joins himself voluntarily to that society in which he believes he has found that profession and worship which is truly acceptable to God.

Contrast the Lockean view to that of the Heidelberg Catechism (Q & A 54):

Q. What do you believe concerning “the holy catholic church”?

A. I believe that the Son of God through his Spirit and Word, out of the entire human race, from the beginning of the world to its end, gathers, protects, and preserves for himself a community chosen for eternal life and united in true faith. And of this community I am and always will be a living member.

Historic liberalism is predicated on the assumption that all communities can be reduced to mere voluntary associations of sovereign individuals uniting with each other for specific self-chosen purposes amendable at their own discretion. This is behind the contractarian vision of the state, and it also obviously has relevance for the institutional (or not so institutional) church. Is it mere coincidence that North America, whose culture has been deeply influenced by Locke, is disproportionately populated by churches with voluntaristic polities and a commitment to what has been called "decisional regeneration"?

What if we were to take seriously St. Peter's words concerning the church and the seriousness of God's sovereign call to us as its members?

But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light (1 Peter 2:9).

How would this change our attitude towards the church as corporate recipient of God's grace?