Apart from God’s energies (workings) in creation, the most decisive and important way in which God can be known is through His revelation in Jesus Christ in history. Jesus Christ is the concrete presence of God in history – Jesus is fully human. Jesus is also fully God. For Dietrich Bonhoeffer, this God-man distinction was crucial:
‘Because Jesus is Christ is man, he is present in time and space; because Jesus Christ is God, he is eternally present. The presence of Jesus Christ in the Church, at a particular time and place, is because of the fact that there is one whole person of the God-Man. It is therefore an impossible question to ask how the man Jesus, limited by space and time, can be contemporary with us. This Jesus does not exist in isolation. Equally impossible is the other, how can God be in time. This isolated God does not exist. The only possible and meaningful question is, ‘Who is there, present in time and place?’ The answer is, ‘The one person of the God-Man, Jesus Christ.’ I do not know who the man Jesus Christ is, unless I can at the same time say, ‘Jesus Christ is God’; I do not know who the God Jesus Christ is, unless I can at the same time say, ‘Jesus Christ is man.’ The two factors cannot be isolated, because they are not seperable. God in timeless eternity is not God; Jesus limited by time is not Jesus. Rather we may say that in the Man Jesus, God is God. In this Jesus Christ, God is present. This one God-Man is the starting point of Christology.’ (‘Christ the Center,’ p. 45)
The humanity of Jesus Christ was central for Bonhoeffer – Karl Barth had similar thoughts as well. The basic idea is summed up in the final sentences bolded above. Only if Christ was completely human would the Incarnation have had any meaning for humanity. This forms the foundations of one of the distinctive mark of Bonhoeffers (as well as Barth’s) theology: that God is ‘for us’ in Christ – in the real and complete humanity of Christ, and in the real and complete divinity of Christ, God reconciled the world to Himself.