Much can be learned, by metaphysical intellection, from the comparison of Buddhism and Christianity. In a way, that is the axis of Schuon’s Treasures of Buddhism (formerly In the Tracks of Buddhism) as well as Osborne’s Buddhism and Christianity in the Light of Hinduism. It is at least as instructive to see how they arose from their parents.
As Schuon points out, both Christianity and Buddhism arose not through “reformation” (a charge often made by modern scholars far from the essence of tradition), but through “invasion”; the mission of both the Buddha and the Christ was — as logoic emanations into the phenomenal — to jailbreak the inward methodological functions of primordial traditions held captive in their own pharisaical formalism, and make them available, through proper initiatic processes, to people outside of their original contexts. Contrary to popular belief (backed up, in many cases, by poor academic scholarship), it is entirely possible to fully join — through varying processes — both Hinduism and Judaism. In fact, it always has been possible, or else the Greek devotees could not have joined Jewish worshipers, and Alexander’s men could not have become Hindus. Nevertheless, at the times of their earthly ministries, both Jesus and Siddhartha ran head-long into the rock-hard crystallizations of legalistic formalisms strangling the life out of influential segments of their parent faiths — faiths which, even today, are largely associated with particular national, cultural, and/or racial membership. In order to universalize those methods of liberation, it was necessary to remove them from seeming dependence upon their birth-races.
Both Christianity and Buddhism are initiatory in nature. That is, one is not a Christian or a Buddhist until the proper steps are taken and commitments made, and the inward essences of each tradition remain unavailable — in principle and in practice, whatever Protestants may say — until the aspirant has demonstrated appropriate commitment and internalized certain graces comparable to yogic śaktis. By comparison, there are many degrees of participation in both Judaism and Hinduism in which one remains definitely Jewish or Hindu, and not a mere “nominalist”. It is sufficient, in both cases, to be born in; one cannot be born a Christian or a Buddhist, no matter how many generations of believers led to one’s birth. In Hinduism, it is even sufficient, according to Swami Vivekananda, simply to call oneself a Hindu and inwardly accept the essential doctrines of karma, dharma, and reincarnation. Further initiations are available to qualifying adherents of both faiths, but are not necessarily required to participate in the “life of faith”. True, a lot of study and community involvement is a requirement to join Judaism, however no more than exoteric involvement is demanded in either case.
The initiations of Buddhism and Christianity do differ considerably, but contain similar metaphysical elements. The Christian is baptized first by water, then by fire and Spirit, and only then is brought into the Body of Christ. During this process, she is (ideally) expected to study the Gospel closely, trying to find faith in it and putting it into action in her life. The process is definitely progressive, with one “stage” of initiation occurring only after the previous one has been completed. The full flowering of this process is in awakening the virtues of Faith, Hope, and Love, with Love containing and, as it were, animating the other two. The Buddhist, on the other hand, “takes refuge” simultaneously in Buddha, Dharma, and Sangha, corresponding approximately to saving faith in Jesus the Christ, in God’s Word (more the metaphysical Logos than biblical Scripture), and the mystical Body of Christ. As the Buddhist takes the triple-refuge all at once (though the inner blooming of the refuges may be quite gradual), the Christian must move from one to the next in the stated order. We can say that for the Christian, the first awakens Faith, the second Hope, and the third Love, going from the specific to the general; the corresponding virtues of Buddhism, if I may speak informally, we might call Intelligence, Knowledge, and Compassion.
Judaism most certainly possesses something of the baptismal mystery within it, as does Hinduism, both requiring some degree of ritual purity (depending upon one’s responsibilities). Judaism’s earliest known initiatory esoterism, corresponding to the baptism by the Spirit, was the “prophetic school” of Mount Carmel (which, incidentally, possesses close mystical ties to the Catholic Carmelite Order of genuine esoteric reformers). And, of course, all Jews are considered to be of “one body” in the sense of representing a single, world-influencing compact in service to God. The latter prophets of Judaism, representing the Mount Carmel school and its successors, as seen in the Hebrew Bible, represent the outpouring of Love to those both within and without the Jewish community. This was precisely the kernel which Jesus represented, first to Jews themselves — especially those of His inner circle of disciples, as seen in the esoteric shape of the Sermon on the Mount (presented only to His immediate inner circle, and not, as commonly misread, to the vast crowds from which they retreated for the Sermon) and, after His resurrection and appearance to Saul-cum-Paul and others, to the whole Roman world.
The esoterisms of ancient Hinduism are — as they still are today, given the all-around diversity of Hinduism — much more diverse than those of early Judaism. (Kabbalah is a relatively recent development, though still fully “orthodox” and traditional.) Still, the most well-known of Hindu esoterisms of the days leading up to the life of the Buddha were yogic in nature and, thus, at least mostly “gnostic”, compared to Judaism’s “bhaktic” or “loving-devotional” bent. (Again, this is pre-Kabbalah, as Kabbalah is decidedly gnostic in nature.) As these yogic schools of Hindu esoterism are known to be the ones which the Buddha encountered during his wanderings, it is this sort of approach which serves as the launching-point of Buddhism. Even Christian Gnosticism depends upon a pre-existing base of Faith, Hope, and Love — as the Jewish esoteric base. Primitive Buddhism — leading into Theravada Buddhism and, eventually, most forms of the Mahayana — has intellective meditation developing into unitive contemplation as its pattern. For the Christian, unitive contemplation sprouts from love, while for the Buddhist, universal compassion unfolds from unitive contemplation for, as Ramana Maharshi quipped, how can one mistreat who he knows to be himself?
It should go without saying that these general observations do not dismiss notable exceptions. That all four “poles” of sādhana — “spiritual discipline”, the four poles being karma or charyā (selfless action), bhakti or kriyā (ego-transcending devotion), dhyāna or yoga (“cessation of movements in the consciousness”), and jnāna (gnosis, or pure intellection) — must arise within any complete tradition. As such, Christianity certainly has evidence of a purely contemplative tradition in the form of the rediscovered Gospel of Thomas, and the likes of Meister Eckhart. Buddhism carried the seed of devotional love from the first, which eventually took root and flowered as the various forms of “Amidhism” or so-called “Pure Land” Buddhism. Just as nama-japa is performed by Hindu bhaktas, the Saving Name of Jesus is invoked by hesychasts and their heirs, and some schools of Sufis practice remembrance (dhikr) of the Name of the Prophet, so do Amidhists practice nembutsu or buddhanusmṛti (“rememberance of the Buddha”) in which the name of Amitābha-Buddha (the Buddha of Compassion) is chanted — either alone, or as part of a traditional mantric formula. And, just like the bhaktas and Christian devotees, the purpose of this chanting is achievement of a Paradise from which Nirvāna may be reached much more easily; in other words, it is a vehicle of extra-cosmic Mercy, a horizontal, inclusive, heavenly circle of communion extending outward from the shaft of a vertical ray of Grace; it is a similar “heavenly geometry” to that of the “side effect” or angelic outpouring of the Eucharistic Mass, in which Heaven’s Grace is extended outward from the sacrificial altar of the Church to those open to the influence up to several miles around, though occurring in subtler fields of activity than the material and lower astral.
A distinction between Christianity and Buddhism which is often made — as could, in the same spirit, also be made between Judaism and Hinduism — is that the salvation to which they aspire (or the Absolute which they preach) differs considerably. This is to forget, however, the apophatic essence of Christian theology. It is unfortunately true, due largely to the influence of both sentimentalists and rationalists, that Christians have not given this esoteric center much credit in several centuries and, at least in many forms of Protestantism, sometimes even brand this most orthodox of doctrines as “heresy”, but the degeneracy of intellection in no way degrades Truth. It is true that popular understandings of “heaven” are more like the Paradise of Amidhism than the Nirvāna of contemplative Buddhism (and, of course, Amidhism’s ultimate aim), but God the Father and Nirvāna could just as easily be synonyms. One need look no further than Dionysius the Areopagite to see how Christian mystical theology meets the same formlessness found in Buddhism and the height of Advaita Vedanta and non-dual Saivism (as well as Kabbalah).
Another question ought to be addressed, here: that of exoterism and esoterism. Christianity and Buddhism are, strictly speaking, esoteric religions. By contrast, Judaism is an exoteric tree which produces esoteric fruits; Hinduism is quite a bit different, in that it is a flowering exoteric bush with deep esoteric roots. In Judaism, one begins religious life with exoterism, and could very well pass through life in this mode exclusively, while every Hindu has immediate access to some degree of esoteric teaching and practice. Buddhism, given the cultural environment in which it spent most of its lifetime, has largely been able to retain its obviously esoteric character. Even so, it has built upon itself an exoteric edifice for the benefit of the great mass of followers. Christianity, however, has become almost entirely obscured by its exoterism. It is as if the village outside a fortress wall, extending horizontally around to the edge of the wilderness, entered a growth boom in which it could only grow upward to hide the castle from view. Despite appearances, the castle still stands, and is quite more than a mere tourist destination, but the loud and ugly city outside must be traversed without getting lost in the crowd, and then the wall crossed with the help of a guide possessing appropriate experiential authority. In brief, Christianity most certainly still exists in its original, esoteric “DNA”, but its exoteric outer shell has become a mutated limb with a malignant growth. The grace of the outward Sacraments is still efficacious within those institutions with authentic spiritual succession.
An entire book could be written on these relationships and, indeed, several have been. The preceding have been little more than some metaphysical notes compared to what could be said in this connection. The details stack up as we realize more and more that Christianity and Buddhism present important universalized systems of vital religious doctrines and practices, represented in a form assimilable by peoples well outside of their birth-cultures. The decadent Germanic, Greco-Roman and Celtic religions were not the vehicles of grace the men and women of Europe required, and the traditional doctrines of the far East were very much “this-worldly” and so, while mostly fairly healthy, incomplete. Of course, much could be made of this analysis, and I am necessarily leaving out exceptions and details for the sake of brevity. That, however, is not my present purpose. The present purpose, in sum, is this: salvation comes to the world in the shape and time most necessary. Christianity and Buddhism are still today what they were at their inception: extensions of Heaven’s Grace in a messianic form custom-suited to the Iron Age in which we still live. Those who seek Life in this world have already had a rope — appropriate to their precise needs — thrown to them from shore and need only open their eyes and take hold.