does god actually make a difference?

Does God actually make any difference at all to our efforts to transform the world into a place of justice and peace? This isn't a question about whether or not we ought to be doing it: we ought! The question is, what difference does being a Christian make to our work of transformation, compared with other people and groups who are working towards the same goals but with no Christian reference. What do I say to the young man I know who is passioantely committed to making a difference in the world, but sees no need whatsoever to do is "for Christ's sake". He cannot see that Christian faith adds anything, nor does he see any evidence for some notion of the work of the Spirit that means there is some sort of appreciable difference in either the quality or effectiveness of Christian participation in the struggle for justice. What's the answer here, folks? Is there an answer? And if there isn't, why do we bother about the "God" bit?