… where do we find any justification for imagining that by rightly under taking what the New Testament commands us to do, we are absolved from doing what the Old Testament commands? Why should we imagine that doing evangelism in obedience to the New Testament excludes doing justice in obedience to the Old? Why have we allowed what we call the Great Commission to obscure the twin challenge (endorsed by Jesus himself) of the Great Commandment?
How can it be suggested that evangelistic proclamation is the only essential mission of the church? It seems impossible to me to justify such reductionism if we intend to sustain any claim to be taking the whole Bible seriously as our authority for mission and as that which defines the content and scope of our mission. Mission belongs to God – the biblical God. The message of mission is to be drawn from the whole of God’s biblical revelation. So we cannot simply relegate the powerful message of events such as the exodus or institutions like the jubilee to a bygone era. They are an integral part of the biblical definition of God’s idea of redemption and of God’s requirement for his redeemed people. We pay no compliments to the New Testament and the new and urgent mission of evangelistic mission it entrusts to us in the light of Christ by relegating the Old Testament and the foundations of mission that it had already laid and that Jesus emphatically endorsed. Whole Christian mission is built on the whole Christian Bible.
From The Mission of God: Unlocking the Bible’s Grand Narrative pages 304 and 306.