This little quote comes from Works of Love:
If anyone thinks he is a Christian and yet is indifferent towards his being a Christian, then he really is not one at all. What would we think of a man who affirmed that he was in love and also that is was a matter of indifference to him?
K. can be rather blunt at times.
This, blunt as it is, is a hugely important statement. To overlook it would be a sign of that indifference that K. is condemning here as paganism.
So I stop to consider this statement.
The scriptures support Kierkegaard's analogy to the person in love, noteably in the early chapters of Hosea(describing Israel's relation to God) and in the book of Revelation, where the church is freqently described as the Bride of Christ.
I'm also reminded of C. S. Lewis's conclusions in the essay "A Slip of the Tongue"(from The Weight of Glory, and a half-dozen other essay collections, if I had to guess):
For each of us the Baptist's words are true: "He must increase and I must decrease." He will be infinitely merciful to our repeated failures; I know no promise that He will accept a deliberate compromise. For He has, in the last resort, nothing to give us but Himself; and He can give that only insofar as our self-affirming will retires and makes room for Him in our souls. Let us make up our minds to it; there will be nothing "of our own" left over to live on, no "ordinary" life.
Scripture describes marriage as the two individuals becoming "one flesh." Lewis sees our marriage to Christ as apart of the Bride as more involved, making room for Him in our souls. This, this call to decrease while the LORD in us increases, is not something done easily, much less indifferently. Yet this is commitment of the wedding of the church to Christ. Each of us as members of this body must be continually giving up ourselves to make room for the Spirit of God in us. This is what it means to follow Christ, to take up the cross as Christ did after relinquishing His will to that of His Father, this is what it means to be a Christian, and the giving up of your whole identity for the substitute of some new creation cannot be done indifferently; that's simply a contradiction.
The church today must recognize this. There's no "ordinary" life, separate from the life in Christ for the new creation; life cannot be compartmentalized to make it so. That is, scripturally, not what God is talking about when describing His Bride. Our calling, to love the Lord, to love people, to go and sin no more, to go tell, with all of the layers, is a constant, better to be lived not at all than only on Sundays(Rev. 3).
The only course of action that the LORD leaves open to His followers is that of decreasing, that is, becoming the new creation that the Spirit in us will create when we let Him increase and live through us.