Here's a surprise: the word "Scientology" was first invented in 1875 by linguistically creative author, Stephen Pearl Andrews, as part and parcel of a tome chock full of comparable coinages, titled The Primary Synopsis of Universology and Alwato (which, Andrews blithely assures readers, will be "the new scientific universal language"; don't ask me what Alwato means).

The word is described thusly in the ornately written 'Table of Contents':
Scientology, the Science of the Scientismus, or of that Secondary Department of Being, or Stage of Evolution, in which Scientism, the Spirit or Principle of Science (or of that which is analogous with Science) preponderates—strict, legal, and law-abiding; Formal, regular; characterized by straightness, accuracy, and adjustment; as of Straight Lines, Parallelisms, Rectangularities, Squares, Cubes, etc. (See Index.)
And here's a sample of its use amongst the writing of which the book is strung together:

58. SCIENTOLOGY, is, on the contrary [to Naturology], that Branch or Aspect of Universology in which the Universe is considered and treated as consecutively and logically evolved from the Three Abstract Universal Principles above specified (2, 45), related to the Three Primary Numbers. It is, in other words, the Logical and Mathematical Evolution of Being universally, from the Primordial Categories or Basis-Thoughts of Being. Scientology is therefore Universology developed in the spirit of the Exact Sciences, and is wholly new in kind. It is the Core or Centre and the most distinctive Department of Universology, that in which the discovery of this New Universal Science mainly consists; but it is proportionally less popular, in character, and more remote from old and existing scientific ideas.
The paragraph numbering, incidentally, is present throughout the book, which his 250 such paragraphs from beginning to end (though many of these run a page and a half, and some are simply lengthy 'testimonial' quotes by asserted authorities on the subjects covered). Towards the end of the book is a "condensed account," which the author explains was "requested by the publisher"-- who was apparently as flummoxed by Andrews' inventive vocabulary as, well, any typical reader would be.

'Scientology' is but one of many sentimentations invented by Mr. Andrews. It is 'Universology' which is the core subject proposed by this author. And though Mr. Andrews incorporates the study of prevailing religious views into his system (under the title of 'Theandric'), his is no work of theology. It appears mostly concerned with the arrangement, organization, and designation of scientific fields. And lastly (in case you were wondering), no, the book makes no mention of alien spirits deleteriously attaching themselves to human souls as a result of mass genocide in Earth volcanoes at the direction of an evil alien overlord (though one still must wonder whether L. Ron Hubbard ever happened to come across this book while seeking inspiration for his own invention).