Teaching "Those Who Are Ripe"
Despite the general Buddhist principle that a spiritual teacher may not teach others unless explicitly requested, Buddha allowed exceptions in the case of potential disciples who were especially ripe. A spiritual teacher, however, needs advanced extrasensory abilities to recognize correctly when someone is ripe. Those lacking such abilities may easily abuse the dispensation and fall to the extreme of becoming proselytizing missionaries. Even if one is not in the position of being a teacher, one might patronize other religions, or Buddhist traditions other than one's own, and think that they are perfectly suitable for feebler, less spiritually developed minds. When holders of inferior views become more mature and "ripen," they will be ready for the more profound Buddhist teachings of one's own tradition.
The lesson here is that one needs great care nowadays when making the Buddhist teachings available in order to "provide the circumstances for other's good karma to ripen to become Buddhists." One needs nonattachment to Buddhism and a truly nonpartisan attitude of respect for all religions; otherwise, one's naïve good intentions may mask a chauvinistic missionary mentality to spread the true word.
Conversion by Showing Deeper Meanings of Others' Scriptures
Nevertheless, Buddhists have traditionally engaged proponents of other belief systems in philosophical debates, whether or not with the motive of conversion. What is the Buddhist method for convincing others of the superior logic of the Buddhist path? As the 8th-century C.E. Indian master Shantideva explains, two parties can successfully debate only when based on using examples that both sides accept. Without a common basis for discussion, they have no meeting point. Thus, as the commentaries explain, the First Kalki's intention was to wean the brahmans from attachment to their literal reading of the Vedas, by showing them alternative, deeper ways of understanding some of the topics discussed in them.
An example accepted in common by the Vedas and Tantric Buddhism is the injunction to take life and to eat flesh. In Buddhist tantra, the two have hidden meanings. Taking life refers to taking the life of the disturbing emotions, which means to take the life of the energy-winds on which they course through the subtle body. Cattle represent the disturbing emotion of naïveté, a form of unawareness (ignorance). Eating their flesh means to bring the energy-winds of naïveté into the central channel and to dissolve them there. The Vedic injunction to sacrifice bulls and to enjoy their flesh can also be read with the same hidden meaning in reference to an inner yoga dealing with the subtle energies. Manjushri Yashas used Vedic terms and concepts in this way to lead the brahmans to the Kalachakra path to liberation and enlightenment.
In Buddhism, then, a skillful method for "converting" followers of other religions avoids refuting the doctrines of their creeds, but shows instead alternative ways of interpreting them. In examining, as when buying gold, the deeper meanings of their own texts as revealed by Buddhism, they will become convinced of the validity of the Buddhist path. People's religions of origin thus become valid stepping-stones on the Buddhist path, if they should choose to pursue it.
A clever mind, however, can fabricate elaborate and beautiful intellectual schemes to show that the concepts of any system actually have the deeper meaning of the concepts of another. Motivation is essential; although, again, is it easy to rationalize by saying that one compassionately wishes to lead others to liberation and enlightenment. After all, with compassion, one could equally wish to lead others to heavenly salvation or to an economic and political paradise. To avoid the pitfalls of arrogance and doctrinal chauvinism, one needs sincere respect for other systems of belief and for those who follow them.
Conversion without Totally Rejecting One's Previous Views
The acceptance of Buddhism, then, does not entail total rejection of all one's previous views. It is not a formal renunciation of one's former religion, as when converting to a biblical faith. One may still take provisional refuge in the god or gods of another religion, just not ultimate safe direction. What one needs to reject completely is only one's previous "distorted views." These are defined not simply as views that differ from Buddha's deepest intentions, but as views that are also antagonistic toward them. If one overcomes aggressive antagonism toward Buddhism -- and, it is reasonable to add, aggressive antagonism toward all other religions and systems in general -- some of one's previous views may act as stepping stones. Tibetan Buddhism uses the same stepping-stone method to lead its followers along a path of progressively more sophisticated Buddhist systems of philosophical tenets, from Vaibhashika to Madhyamaka.