It’s the same school, but the book that said not to combine practices was called “Oaths and Vows”, however even in this study, she does separate the Northern Tradition and the Abrahamic Tradition. Here’s how she puts it:
“Masters of various traditions use different tools to achieve this effect: (how to weave the fabric of reality).
A Mage of the Christian tradition influences reality through prayers and incantations;
A Voodoo Mage or shaman uses his connection to the spirit world, and through tools and abilities given to him by his tradition, he achieves the desired effect;
A Kabbalist applies spells and invocations through magical formulas that work in the tradition of his worldview and religion.
The Rune Master uses runes, and unlike the masters of other traditions, he sees in the runes something that others do not see - the facets of this world, it’s keys, nodal points of the event formation. By influencing these keys via runes, he changes reality.”
She’s not anti- Abrahamic Tradition for she goes onto say,
“this book — is not to argue about whose cultural tradition is older. We are all children of the Earth and came from a single tribe.”
She then speaks of egregore, a term I’m unfamiliar with. It’s here where she keeps the two traditions separate. Here’s what she says:
“Everything that once dominated her (she’s referring to a student as an example) mind and was part of the culture in which she lived needs to be revisited and re-evaluated. The Christian tradition is built on the belief of sin, guilt, for which mankind is a slave to be redeemed by God, however the Northern Tradition is built on freedom, the right to be human, no sin.”
It’s upon these differences that she states that the two traditions are in conflict with each other. I haven’t read this in any other book, and as it’s not a dominant feature in this one ( whereas in the Oath and Vow book it was), I’m inclined to pass over this.
Other books I’ve read regarding Christianity and the Northern Tradition have a more balanced view, in that they state (AsatruUK as one example), the Abrahamic Tradition when it came to England was gradually absorbed into the consciousness of the Heathens and vice-versa, even though the Church did make illegal, certain heathen practices to promote Christianity, the Heathens themselves practiced both, privately, without issue.
I hope this explains it. I’ll probably learn alot more as I go through the course. 
Note, this is a Russian school, so I don’t know the history of Russia and the effect of Christianity on Russian pagans, which of course may influence her world view. 