6. The whole counsel of God, concerning all things necessary for his own glory and for mankind’s salvation, faith and life, is either expressly written down in Scripture or may be deduced from Scripture by good and necessary consequences. Nothing at any time is to be added to Scripture, whether by new revelations of the Spirit or the traditions of mankind. Nevertheless, we acknowledge the inward illumination of the Spirit of God to be necessary for the saving understanding of such things as are revealed in the Word, and we acknowledge that there are some circumstances concerning the worship of God and government of the Church, common to human actions and societies, that are to be ordered by the light of nature and Christian prudence, according to the general rules of the Word, which are always to be observed. (WCF 1.6)
One of the first things that they teach you when becoming a pilot is “trust your instruments!” That was told to me by an extremely well travelled friend of mine who has flown planes to every part of the globe, and that phrase “trust your instruments” has stuck, why? Because he told me that no matter what you feel or how much experience you might think you have, when your up there in the air your instruments can be the difference between landing safely on the tarmac or hitting the ocean floor. Now I mention this because that’s what the Westminster Confession is getting us to see here; the Christian life is a journey and God has given instruments to His church so that we might sojourn safely. The instruments (talked about here at least) are the bible and the Holy Spirit (2 Pet 1:20-21; Jn 14:15-31,15:26-27), and understanding God by and through His “special revelation” is the difference between spiritual blessedness or total ruin (Ps 119).
You see the confession wasn’t written in a vacuum. Historically, on the one hand, the church was kicking back against the Roman Catholic traditions that hadn’t yet been “weeded out” of the church of England, and on the other hand, against a movement known as “the Anabaptists” whose many and various teachers claimed to have had “private revelations” which would be on par or even trump scripture (they of course would all contradict one another c.f. Gal 1:6-9, 2 Thess 2:2). The confession says no, you want to know what is sufficient for the church’s life and doctrine? It’s found in what God has given so that we might be “complete and equipped for every good work.” (2 Tim 3:17 ESV). In other words, the church is called to trust in “the instruments” that God has given us because He has given everything we need in order to be saved and lead a life of faith that is pleasing to Him (Jn 6:45, 1 Cor 11:13-14, 14:26,40). However, the confession acknowledges that the Bible doesn’t always command every “what and how” in regards to every ecclesiastical practice and thus the church needs to sometimes do the hard work of “deducing” what God would have us to do (how we administer baptism, how old you have to be to take the Lord’s Supper for examples). But this is where the confession brings us right back to where we need to be, it might not be clear, but we reason and work out what we should practice by and from the 66 books of our God-breathed scriptures.
A couple of things to note here as we think on these things. First, the confession rejects “new revelations” from the Holy Spirit, but in no way does it reject the Spirit’s very personal and very on-going work in the lives of His people. No, the third person of the Trinity is vitally important as it is He who “illuminates” the truths that have always been in the scriptures so that we might apply them to our context (1 Cor 2:9-12, Eph 1:17-18). It is He who will lead and guide us into all truth (Jn 16:13). Second, as the confession wasn’t written in a vacuum, neither do we live in one and thus because of God’s good ordering in His creation, the church can actually take note of and apply truths found in “common human actions and societies”. We are to worship God; do we meet for two hours or five? Do we meet once or twice on a Sunday? Do we meet in a building or in homes? We are to have elders; do we have two or ten? We are to preach the word; what translation do we use? How long should a sermon be? The bible is silent on these sorts of questions, though what matters is that “the general rules of the Word are always to be observed” meaning that which God has made clear we are to follow and thus the rest we must ask for His wisdom so that we might together as His people work it out in love and Christian unity.