“I don’t see the word Trinity in the Bible,” says the Jehovah’s Witness knocking on your door. “There are no Bible verses that say we shouldn’t speed,” argues the angry church member who’s been pulled over by the police for the tenth time. “I can’t see a clear example of a woman taking the Lord’s Supper in Scripture,” worries the newly converted single mom. And they’re right, aren’t they?

As evangelicals, we rightly want to be people of the Word. We treasure the Bible as the Spirit-breathed Word of God. We acknowledge it to be without error, sufficient for our every need as disciples. We recognize it as our supreme authority, coming, as it does, from our Lord and King. But is this authoritative Word limited to the words of the text alone? Our Reformed forefathers thought not. Take this paragraph from the Westminster Confession of Faith: “The whole counsel of God concerning all things necessary for his own glory, man’s salvation, faith and life, is either expressly set down in Scripture, or by good and necessary consequence may be deduced from Scripture” (WCF 1.6).

The key phrase for our purposes is, “by good and necessary consequence may be deduced from Scripture.” Put simply, this means that not just the explicit text but also those truths that unavoidably arise from the text are also part of the meaning of God’s Word. So, consider our speeding driver. Is there a specific Scripture on speed limits? Clearly not. But if we consider our duty to obey those earthly authorities God sets over us (Rom. 13:1–7), we are justified in claiming that it is not just the police but God who wants us to obey speed limits. Is there an explicit example of a woman eating the Lord’s Supper? Perhaps not. But once we’ve carefully put together texts on the place of women in the church and the purpose of the supper, we should conclude not just that Christian women may take communion, but that they must unless they are under church discipline. All other things being equal, it would be wrong to refuse to admit to the supper on account of their gender someone who credibly professes faith in Christ or for our nervous newly converted mom to abstain.

But the particular concern I want to address in relation to “good and necessary consequence” is pastoral. Namely, we must learn to distinguish between “good” consequences and “necessary” ones. Failure to do so will lead either to a legalistic or a disobedient life. In short, unless a teaching we have derived from Scripture is both good and necessary, we may not use it to bind others.