The other day I was attempting to explain to a Christian visitor what Amida-shu Pureland Buddhism was all about. There are interesting correspondences. Is the trikaya doctrine the same as the Christian trinity?
There are certainly some strong parallels and, if you like, you can make them stronger or weaker depending on your choice of language when you translate the meaning of the terms. The trikaya can be the Buddha as absolute truth, spiritual presence and transforming manifestation. Nirmanakaya is Buddha as he acts in the world. Sambhogakaya is the spiritual bliss he enjoys. Dharmakaya is the truth he knows. So the Buddhist trinity is three bodies of one person whereasw the Christian trinity is three persons. There has been a good deal of trinitarian theology that has taken advantage of the three person's idea to advance the notion that God is social - God has relations with himself - God the son talks to God the father. Therefore, sociality is deemed part of divine nature. This is an interesting development in theology. Buddhism is also social in that its other trinity, Buddha, Dharma and Sangha, includes refuge in sangha thus making Buddhism a church in its core nature not just as a consequence of the need to organise in order to spread the Dharma. The sangha is an aspect of Dharma, not just a vehicle for it. The trikaya doctrine does not seem to have a built in sociality, but it does not oppose it in any way. So trinitarian doctrines are valuable but do not all map onto one another with precision.