I am told that Francis Schaeffer was the intellectual guru of his day. The Mark of a Christian is a short meditation on the words of Jesus in John 13 and John 17. Schaeffer is concerned about how well (and more often, how poorly) Christians love one another. Throughout he calls the body of Christ to love another as Jesus commanded. It is not enough to simply love the lost. It is not enough to simply love those in your group (Free Methodists in my case). We must love all those who belong to the body of Christ, even in the midst of our doctrinal differences.
His argument is that if Christians fail to love each other in a visible way then the world has the right to come to two conclusions – that we are not Christians and that God did not send his Son.
A very challenging book that calls us to love in the midst of division and discipline. We are called to maintain holiness and purity without sacrificing mercy and love.