I earlier mentioned the two commandments Jesus gave us about the world. One, we are supposed to come out from among them and be separate. Second, we are supposed to make disciples of all nations. We might think at first that there is a tension or contradiction here. But God’s commands do not conflict with one another, when they are rightly understood.
I wonder if, prior to Christ, Jewish scholars ever got into arguments about the nature of the Messiah. “I tell you, he will be a suffering servant!” “No, he will be a glorious king!” “Servant!” “King!” “Servant!” How could they have possibly known they were both right? And is it possible that the same goes when we argue “Separation and holiness!” “Evangelism!” “Separation and holiness!” “Evangelism!”
God is a God of paradoxes. Want to gain your life? Lose it. Want to be great? Humble yourself and be a servant. The meek shall inherit the earth. The King was born in a manger. Pray for your enemies and bless those who persecute you.
It should come as no suprise, then, that we win the world by separating from it. This is how we fulfill the two mandates of “come out from among them, and be ye separate” and “go ye therefore to all nations”.
A city set on a hill cannot be hidden, because it is on the hill and not on the plain. It’s set up, separated, from the plain around it. The lamp is visible because it’s on the lampstand. Take a candle or an electric lantern into a dark room. Hold it up and notice how much light it gives off. Then set it on the floor and compare. The actual output in lumens is the same, but when the lantern is lifted up and set apart from what it’s illuminating, the light is far more visible.
We live separated, different lives out of loyalty to Christ. The contrast between our lives and the rest of the world is what makes us visible. We walk in wisdom toward them that are without. We are separated from the wicked in our relationships (2 Corinthians 6:14) and the way we live our lives (1 John 2:15-16).
Jesus said that the world would believe the gospel because of how believers treated one another (John 17:22-23). There’s little in the Bible to suggest that the world will believe because of how we interact with the world. The only thing that comes to mind is Paul’s admonition to be kind, gentle, and patient with unbelievers (2 Timothy 2:24-26). But primarily, as a friend of mine puts it, Christians ought to treat each other so well that the world gets jealous.
Of course, total isolation or segregation from the world is impossible and undesirable. We would have to physically leave the world. We will interact with the world as we go about our daily business, and of course there are certain relationships (e.g., family, co-workers, neighbors) that we will have with unbelievers. For example, Paul writes in 1 Corinthians 10 that it’s perfectly appropriate for us to accept invitations to eat with unbelievers (although even then he warns us to be careful). That is why we must “be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear” (1 Peter 3:15), to “walk in wisdcom toward them that are without, redeeming the time”, and to “let your speech be always with grace, seasoned with salt, that ye may know how ye ought to answer every man” (Col 4:5-6).
This has been disparagingly referred to as “incidental evangelism”. But I think it is Biblical.
Some people are called as missionaries, to take the gospel to other peoples and lands. Praise God for them! We are not all called to be missionaries in that sense, though. For most of us, we sanctify God in our hearts, be ready and willing to answer questions about our faith, and expect to be reviled for it (1 Peter 3:14-17). Jesus said the world would hate us.
We must separate from the world because the world is an enemy to God. Friendship with the world is enmity to God. Worldliness – appropriating the values and customs common to people ruled by Satan – is not compatible with building the kingdom of God. So we must separate from it.
But this also means that we will be visible by virtue of being separated. The distinct lives we live will be obvious. They must be, if there is any difference between serving Christ or serving Satan.
Separation from the world is the only way to effectively build up the kingdom of God, and is the only way to let our light shine before men.