When Thomas Merton said that the writings of even Christian mystics were regarded with trepidation in Catholic contemplative monasteries (cf. Mystics and Zen Masters, p. vii) he was, in a subtle way, suggesting to the reader that the West has no high regard for mysticism. The irony of course, is that Zen Buddhism in the West is Oriental mysticism; perhaps the finest example of mysticism the world has ever known. It is not like Christian mysticism although it is not without some kinship depending who is the Christian mystic.
This all leads us to the question of what exactly do we mean by mysticism? The Zennist might answer, it is about personally experiencing our true nature which is absolutely unconditioned. The Christian, on the other hand, might say, if he is Greek Orthodox, it is theosis or union with God. Both are, in fact, speaking about a direct and immediate experience of the sacred or we could even say, the transcendent which lies beyond the corporeal (i.e., the conditioned). Such an experience, I need add, is self-authenticating—it is its own proof. It needs no external verification.
The idea that both Zen and Christian mysticism are ineffable and outside the purview of the religious masses, makes mysticism somewhat unpopular since the adept has to undergo a great struggle, having to leave—if not renounce—his conditioned, temporal world, for a higher. In this regard, mysticism can seem to transcend the aims and values of religion which the masses hold dear.
As far as true faith is concerned none have it in greater abundance than the beginning mystic. The faith of the masses, on the other hand, is in the conditioned world, not the unconditioned higher world which the mystic is in direct communion with. The masses are unwilling to give up their lower faith. They want proof before they might ever seriously consider a mystical journey. This is why we see Zen Buddhism dumbed down so much. It is trying to tell to those who practice at a Zen Buddhist temple and do zazen that their faith in this world is okay. It is all about the here and the now. Such people need not doubt their faith in the mundane world!
Yet, Zen never speaks for this mundane world as if to suggest that the mind of birth and death that washes a monk's begging bowl or chops wood and carries water is the same as the One Mind, or the unborn Mind, that washes a bowl or chops wood. Key here is not the actions but whether or not one has realized the unconditioned absolute when they pick up a bucket of water.
Zen masters of the T'ang dynasty and earlier were quite capable of speaking as mystics; of saying profound things and commenting on the Buddha's most esoteric discourses. Today, this has all but changed. Zen masters are more like psychologists who minister to the masses whose faith in the mundane is in constant need of repair. Even though the mundane world of the masses is falling apart at the seams none dare question it; none dare question its many delusions, its overt hostility towards life, and its path of desire for what is finite and mortal.