NEITHER Eliahu Inbal nor the Frankfurt Radio Symphony Orchestra, whose conductor he has been since 1974, is a very familiar entity in our country, though they toured here two years ago and have made a few recordings for Philips. Inbal is a very able conductor, with a more than respectable orchestra, but nothing they have done before could have prepared anyone for the conviction and persuasiveness that illumine their four-disc set of all the symphonies of Alexander Scriabin (Philips 6769.041).

Scriabin (1873-1915) has been regarded as little more than a cult figure, and his cult has never been a large one. He encouraged this "cultism" himself. The mysticism that is implicit in his harmonies and made explicit in some of his titles and annotations was expanded in his statements on philosophy, art and The Meaning of Life.

He began his philosophical-mystical involvement as a young man, under the influence of Wagner, Nietzsche and other philosophers. By 1904, the year in which he completed his Third Symphony ("The Divine Poem"), he had taken to "preaching to a little circle of people who understand me perfectly and follow me" in his theories of art "uniting with philosophy and religion in an indivisible whole to form a new gospel . . . "

In his personal life Scriabin was the freest of free spirits, exhibiting a sickly but fascinating glaze of reckless selfishness and irresponsibility, yet untouched by pettiness or viciousness. He had a messianic effect on many musicians, and inspired the most profound loyalties. When he chose to leave his wife, Vera, the mother of his four children, to live with his young former pupil Tatiana Schooezer, Vera not only copied out the score of his Third Symphony for him but traveled to Paris for the premiere.

When Scriabin and Tatiana, who had by then borne him the first of their three children, came to New York for programs of his music in 1906, they found themselves threatened with charges of "moral turpitude" and fled back to Europe. There his music was performed widely during the remainder of his life, but less and less during the 50 years following his death.

Scriabin's piano music did come into its own back in the mid-'60s, and suddenly we had four "integral" recordings of his sonatas. "The Poem of Ecstasy," the symphonic poem which Scriabin also called his Fourth Symphony, has been recorded several times and actually turns up on concert programs now and then. "Prometheus, the Poem of Fire," sometimes called the Fifth Symphony, is heard a bit less, perhaps because it requires not only a solo pianist--in a less than concerto-sized role--but also an organ and chorus (and originally a "color organ" to project specified colors during the performance). The three full-scale symphonies numbered as such are still novelties, both in the concert hall and on records; all five of these works are in the new Philips set.

The First Symphony (1900) is in six movements. The first two actually constitute an allegro with a slow introduction, while the sixth is a sort of epilogue, in which solo alto and tenor, with chorus, sing a "hymn to art." (The vocalists here are Doris Soffel, Fausto Tenzi and the Frankfurter Kantorei.)

The Second, hailed as "the new Bible" by Vasily Safonov, who conducted its premiere in 1903, is in five movements; the first two are played without pause, as are the last two, giving the impression of the tripartite form to come in the broader and freer Third of 1905. The Third is "The Divine Poem" in which Scriabin sought to represent "the evolution of the human spirit which, freed from the legends and mysteries of the past . . . passes through Pantheism and achieves a joyful and exhilarating affirmation of its liberty and its unity with the universe."

The almost unparalleled intensity and constant emotional surge of Scriabin's music tend, perhaps, to make his orchestral writing hard to penetrate at times. Themes tend to be fragmentary, subservient to a rhythmic pulse that is always prominent, sometimes quirky; and the blaze of colors sometimes produces a certain congestion, which can appear amorphous rather than brilliant.

What distinguishes Inbal's approach is the way he cleans up the textures and clarifies the line, giving these works a very direct sort of impact without diminishing their "mystic" character.

For those who have yet to explore these symphonies, Inbal makes such an expedition rewarding. If the relatively familiar "Poem of Ecstasy" and "Prometheus" receive somewhat less striking performances here (surely London will have to reissue Stokowski's stunning version of the former work, though both Maazel, on that label, and Abbado on DG, do nobly by it), they are certainly very satisfying ones. Wolfgang Saschowa is the pianist in "Prometheus," with the Kantorei again.