 Within the Christian framework, a number of arguments for toleration have been developed, based on charity and love for those who err, for example, or on the idea of the two kingdoms and of limited human authority in matters of religious truth, i.e., in matters of the divine kingdom. The most important and far-reaching justification of toleration, however, is the principle credere non potest nisi volens, which holds that only faith based on inner conviction is pleasing to God, and that such faith has to develop from within, without external compulsion. Conscience therefore must not be and cannot be forced to adopt a certain faith, even if it were the true one. Yet, Augustine who defends these arguments in his earlier writings, later (when confronted with the danger of a schism between Roman Catholics and the so-called Donatists) came to the conclusion that the same reasons of love, of the two kingdoms and of the freedom of conscience could also make intolerance and the use of force into a Christian duty, if it were the only way to save the soul of another (esp. Augustine 408, letter # 93). He cites numerous examples of reconverted Catholics to substantiate his position that the proper use of force combined with the right teaching can shake men loose from the wrong faith and open up their eyes so as to accept the truth—still “from within.” Accordingly, individual conscience can and sometimes must be subjected to force. Christian arguments thus both form the core of many modern justifications of toleration and yet are janus-faced, always bound by the superior aim to serve the true faith. Similar to Augustine, Thomas Aquinas later developed a number of reasons for limited and conditional toleration, drawing especially strong limits against tolerating any form of heresy.