The Donatist controversy also played an important part in Augustine's thought. The Donatists insisted that the church must be pure and the sacraments were effective only when they were administered by a pure priest. Augustine held that the true church was made of people who are pure, but that the earthly church as we know it is made up of those who are pure and those who are not. According to the teachings of Jesus, this condition must be tolerated To insist that the sacraments work only when they are administered by a priest who is pure is not practical. How is one to know whether a priest is really pure?
Even more important, calling for a pure priest makes the sacraments and salvation depend on human effort. It leads away from depending solely on the grace of God Augustine saw the sacraments as signs or occasions for the invisible grace of God to operate Because the sacraments depend on God's grace and not on the efforts of humans, they operate even if the person who administers them is not pure. According to Augustine, it was only necessary that the sacraments have the proper matter (water for baptism, bread and wine for the Eucharist) and correct form (consecration by the priest) for them to operate That did not mean that there was no place for the true church in the sacraments. Baptism washes away sin, but what that means to a person's life is realized only in the catholic, or universal, church.
Although Augustine did not question whether their sacraments were valid, he did see the Donatists destroying the unity of the church He also doubted that the fullness of the Christian life could be realized outside the universal church. These things led him to consider if force should be used to bring Donatists back into the catholic church. This resulted in his Theory of Just War. According to him, a war is just if it: (1) is fought under the leadership of proper authorities, (2) has as its goal restoring peace or upholding justice, (3) is motivated by love, not greed or the desire for power, (4) has a reasonable chance to succeed, and (5) is fought to benefit society This theory has had wide impact in later Christian history. It formed one of the justifications for the Crusades. It was used to justify the use of force against the powerless by proper authorities (the powerful). It was even used by the church as a reason to persecute, torture, and kill those who disagreed with it (The church ra-
tionalized that these things were all right if they were motivated by love In Christian love, it was better that the body of a heretic died if the soul were saved!)