Quite. Eckhart is so often the go-to mystic for many because:
a) he was condemned by the Church which is always good news;
b) his language is more metaphysical than theological so it can be read from many different confessional perspectives;
c) people are not usually
au fait with where Eckhart stands in the Christian Mystical tradition generally, and Dominican spirituality specifically.
a) The accusations against Eckhart's teachings were examined in 1325 by a papal official, Nicholas of Strasburg, and declared “orthodox.”
A year later Eckhart was again accused of heresy. He wrote his 'Defence' to show his teachings were rooted in Scripture and the Fathers, notably Augustine. Scholars generally agree the accusations stem from a rivalry between the Dominican and the Franciscan orders. His accusers were Franciscans, and so were his interrogators.
The theological grounds of the dispute between the Franciscans and the Dominicans was one of the priority of the will over the intellect (Franciscan) or intellect over the will (Dominican). Eckhart, of course, was totally Dominican, and his preachings all spoke of the 'transcendent intellect' – this is
not the intellect as we read it today, the measure of mental dexterity and capacity, but rather for the medievals, the intellect signified the transcendent, inspiration, intuition and revelation.
The verdict went against him, so Eckhart appealed to Pope John XXII. Eckhart died while the issue was under review and the next year, Pope John XXII, at the behest of his political allies, condemned Eckhart, identifying 17 points of his teaching as heretically unorthodox and 11 as “evil-sounding, rash and suspect of heresy.” The papal bull of condemnation intended to taint his good name and stamp out his writings. It failed.
In the 20th century, Dominican scholars labored to clear his name. The Walberberg Chapter, a panel of experts, convened from 1982-1992. They decided Eckhart
needed no “rehabilitation” in the juridical sense, for neither he nor his doctrine had in fact been condemned, contrary to what had been thought. Heresy implies a deliberate, wilful teaching contrary to Church doctrine, and Eckhart had been unyielding in claiming his views were rooted in Scripture and Church Fathers, and furthermore that if the Church found him at fault, he would recant the teachings! As a heretic must be allowed the option to recant, the fact that he was dead means the accusation cannot now be levelled against him. His ideas are another matter, but again it is universally agreed that his teachings were misinterpreted, and often wilfully so, by his detractors.
John XXII was himself accused of heresy, but the issue was unresolved until his death. Subsequently Pope Benedict XII issued a doctrine that renders John's position heretical, but as this definition was not in place in John's day, he is not himself said to be a heretic. He was a crap theologian, however!
The ruling is one of things easy to understand, but few bother.
The exoneration of Eckhart was “a judgment sustained today by scores of theologians and historians.” (Woods)
In 1992, the Master of the Dominican Order Timothy Radcliffe formally requested Cardinal Ratzinger (later Pope Benedict XVI) to abrogate the bull of condemnation; though this has not yet occurred, Pope John Paul II himself in September 1985 observed, “Did not Eckhart teach his disciples: ‘All that God asks you most pressingly is to go out of yourself … and let God be God in you?’ One could think that in separating himself from creatures, the mystic leaves his brothers, humanity, behind. The same Eckhart affirms that, on the contrary, the mystic is marvelously present to them on the only level where he can truly reach them, that is, in God.” (L’Osservatore Romano, 28 Oct. 1985) Furthermore JP-II said the bull itself was defective and that it did not stand, so there was no need to abrogate it. Dominican scholar Richard Woods concludes: “For all practical purposes, the exoneration of Meister Eckhart has been achieved.” So the Meister can openly be considered as he was in his own day: “one of the greatest masters of Western spirituality” (Colledge & McGinn).
b) – Everyone claims Eckhart's doctrine as 'theirs' because he speaks of a pure metaphysic and not in the confessional language of this doctrine or that!
So he's been claimed by various heterodox Christians (e.g. Matthew Fox's 'creation spirituality'), by philosophers (e.g. Jacques Derrida), By spiritual teachers (e.g. Schopenhauer compared Eckhart's views to the teachings of Indian, Christian and Islamic mystics and ascetics: "If we turn from the forms, produced by external circumstances, and go to the root of things, we shall find that Sakyamuni and Meister Eckhart teach the same thing" and "Buddha, Eckhardt, and I all teach essentially the same.")
The Theosophical Society incorporated Eckhart in its notion of Theosophy. So did Steiner's Anthroposophists. So did the rest of the New Age.
Eckart was compared to Shankara's Advaita Vedanta by Rudolf Otto in his 'Mysticism East and West'. Karl Neumann, who translated large parts of the 'Tripitaka', found parallels between Eckhart and Buddhism and D.T. Suzuki said Zen and Eckhart were essentially the same (they're not).
Psychoanalyst and philosopher Erich Fromm drew on Eckhart's writings, and the Meister was a significant influence in developing United Nations Secretary General Dag Hammarskjöld's conception of spiritual growth through selfless service to humanity, as detailed in his book of contemplations called Vägmärken ('Markings').
Everybody loves Eckhart!
But that does not make him a syncretist, a heretic, a humanist, a Buddhist, a Hindu, a Moslem, etc. He is Catholic through-and-through. His teachings, as he shows, are drawn from the Christian Tradition and founded in that Tradition's teachings.
c) There is nothing in Eckhart's metaphysic that is not there in Scripture, and the root of his thought is well-treated in Catholic circles, from Scripture, through Dionysius, St Maximus, Augustine and notably Eriugena (another who's ideas were condemned). Then trace his thinking in line with Dominican speculation, and it's all there.
The best book I've read is
Meister Eckhart on Divine Knowledge by C.F. Kelley. There's an interesting article by the Moslem scholar Reza Shah-Kazemi on the Sacred Web site.
http://www.sacredweb.com/online_articles/sw10_shahkazemi.html