The objective of his book is plainly stated in its preface,
In this volume, the author will show the meaning of the "Word" which became flesh and dwelt among men, and explain the enigmas and allegories of the Old and New Testaments, proving conclusively by the Bible that astrology is that Word, and written from the beginning; the meaning of the miracles of the Teacher, his birth and death; the city of the New Jerusalem, and the ordination of Freemasonry, the tabernacle of Moses, and the divine revelation by astrology to the formation of the Roman Catholic religion. Everything will be especially and plainly explained, and hundreds of things never mentioned in any astrological work extant. It will show astrology, or that "which is written" from the beginning, to be unalterable and under fixed and immutable law, and that everything and all things emanate from one Almighty Father, the only God; that by means of this study, or divine science, the life of men, or beasts, or duration of things and all their vicissitudes, as well as the fate of nations, the changes of the weather, the rise and fall of stocks, and every affair of life may be surely prognosticated or predicted. It proves all prophecy to be astrology. It will be purged of all nonsensical claims to anything supernatural, or claim to anything but that which is an exact science, sublime and holy, which has existed longer than we have at present any history, and handed down by the great and wise of the past, those builders of the temples of the sun, or universe, until in its old age its ashes are buried in Roman Catholicism but yet burn in Freemasonry, symbolic of the two opposing forces -- the positive and the negative, heat and cold -- the Sun and Saturn, or good and evil. [...] that by their movements and aspects to each other, and especially the☽ (moon), every incident of the dwellers upon the earth may be known, and that no deviation is possible; [...] In this work will be explained how to read and judge accurately any one's nativity; to calculate all manner of questions; to diagnose disease; to tell a person of the composition of his business; to know what best to pursue, and where best to seek either wealth, health, or fortune. [1, pp iii-v]This is an explicit statement that the book teaches astrology. The irony is he fails to realize this requires supernatural phenomena if it is to work, yet claims to have done away with everything supernatural. (He does, of course, use his naive understanding of magnetism to account for it, although that is but pseudoscience - using scientific words does not make science of a claim. It is intriguing just how often "magnetism" is spoken of in the book, but just as intriguing how seldom he actually showcases any understanding of the phenomenon. By the time he wrote the book, James Clerk Maxwell already had provided a fairly good mathematical basis for understanding the effects of the phenomenon quite some time earlier. I am pretty certain Anderson kept referring to it exactly because so few in his readership would understand it, but defer to his pretend-understanding of it.)
Already in the preface we find a really telling instance of eisegesis:
The entire work will be devoted to the elucidation of astrology as practised by the ancient people, explain the "mystery of the serpent," so as to enable one if so desired to do as the Teacher did when ascertaining if the woman should be adjuged guilty by the Pharisees when he stooped and wrote upon the ground with his finger (i.e., cast a horoscope or horary question), and saw the answer. [1, p. v]In a similar way, Anderson keeps using his own assumptions, inserting them into the text as evidence of these self-same assumptions.
Anderson provides a fanciful history of the origin of astrology:
Yet did they carefully note the effects of different configurations, and noticed magnetic changes take place upon the earth as the sun and moon were aspected differently by the planets, and through them passed this magnetism to each other as well as upon the earth and the inhabitants thereof, as well as all things upon it [...]As the earth revolved, every degree and minute and second of degree was carefully noted for year after year, till the planets had gone through all their multitudinous changes, and then they were able to say what would happen to a person born at such an hour and minute, with such and such configurations or magnetic rays affecting him, or would produce for the future; [1. p. 4]For the planets to go through all their changes in relation to each other for every second of a degree, the size of the records that would have to be kept rival the surface size of the north American continent. Surely, such records would have left some trace - even the industry required to obtain material for such records in ancient times would have left quite obvious and clear remains.
Any number of claims Anderson made can be rejected without further investigation - his confusion as to linguistics, the Hebrew language, history and so on are all impressively obvious. Let me point to one more example:
It is plainly shown by the writer of Genesis that not only the period of caloric or heated cycle, when the earth was not yet cool enough to precipitate rain, and human life was not yet existent, was meant in this description, but also that a tropical region in a tropical climate was the first abode of man. To digress: our Old Testaments are exceedingly incorrect in much of their rendering of the Hebrew, and therein lies much false reasoning occasioned by such errors. Probably one of the most important of omissions is that of the following: -
GEN ii. 3: "And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made."
Now, a very important omission is here at the end, it is this: "which God created, and made to create by evolution," this omission being לעשות, or laassass; my authority for this being the Rev. Fleurlicht, doctor of divinity and a celebrated Hebrew scholar.[1, p. 120-121]
His failure to provide any sources for his claims reduces his quality as a source even further, and his failure to explain his conclusions using realistic, feasible scenarios or reasoning makes him come off as almost religiously ignorant. It should come as no surprise that this author also believed in Atlantis, in the ancients having incredible knowledge of science and technology, and so on.
In conclusion, Karl Anderson's The Astrology of the Old Testament can only really serve as a source if we want to know what 19th century astrologists believed. D.M. Murdock accepting him as a source on the beliefs of ancient Israelites and early Christians is a strong indicator that she is not a credible scholar.
I may return to this work to point out even more of its flaws in the future, once I have familiarized myself more with it.
 Anderson, Karl; The Astrology of the Old Testament.