‘The truth that is true is true for me’ does not mean arbitrariness or caprice, believing anything one likes. It signifies inner resolve, where the ‘for me’ – an expression, he says, he first found in Luther – means the truth that personally transforms my life. The opposite of ‘true for me’ is a lifeless truth, pure lip service, evading the demands of life with empty words. Seek first the Kingdom of God: that is, the first order of business is to transform one’s own inner life, not the accumulation of external trappings of speculative knowledge. The truth of Christianity is not to supply raw material for the reflections of German metaphysics, no more than it is to be relegated to Sunday morning piety and ignored the rest of the week.
If Christianity is ‘true’ it is true in the sense that Scriptures speak of when it is said of Jesus that he is ‘the way, the truth and the life,’ meaning that its truth is a way of living in the truth. If you do not have in your heart the love of your neighbour of which the New Testament speak; if you are not loving and forgiving your life; if you do not inscribe this love into your personal existence, then you are not ‘in the truth’ in the existential sense.
John D. Caputo, How to Read Kierkegaard (Granta Publications: 2007) p. 13