All Christian mission flows from the cross–as its source, its power, and as that which defines its scope.
It is vital that we see the cross as central and integral to every aspect of holistic, biblical mission–that is, of all we do in the name of the crucified and risen Jesus. It is a mistake, in my view, to think that, while our evangelism must be centred on the cross (as of course it has to be), our social engagement and other forms of practical mission work have some other theological foundation or justification.
Why is the cross just as important across the whole field of mission? Because in all forms of Christian mission in the name of Christ we are confronting the powers of evil and the kingdom of Satan–with all their dismal effects on human life and the wider creation. If we are to proclaim and demonstrate the reality of the reign of God in Christ–that is, if we are to proclaim that Jesus is king, in a world which likes still to chant “we have no king but Caesar” and his many successors, including mammon–then we will be in direct conflict with the usurped reign of the evil one, in all its legion manifestations. The deadly reality of this battle against the powers of evil is the unanimous testimony of those who struggle for justice, for the needs of the poor and oppressed, the sick and the ignorant, and even those who seek to care for and protect God’s creation against exploiters and polluters, just as much as it is the experience of those (frequently the same people) who struggle evangelistically to bring people to faith in Christ as Savior and Lord and plant churches. In all such work we confront the reality of sin and Satan. In all such work are challenging the darkness of the world with the light and good news of Jesus Christ and the reign of God through him.
Christopher J. H. Wright, The Mission of God’s People: A Biblical Theology of the Church’s Mission (Biblical Theology for Life), 109-110.