There are two points I will bring up that justify this:
1. The world was wrought forth by Kroder, who is a demiurgic entity.
2. Frya’s Tex is in essence a manual on achieving gnosis.
First point, the material being a result of the demiurge. Wralda is the supreme being, however the world we live in was created by Kroder (Time). From Wralda's spirit comes the forms, potential, and energy the physical world draws upon.
As we see Kroder/Time is a byproduct of creation itself. The creation story in the OL lends to the idea of evolution, as life sprung from Jrtha and the passage of time. Life of course only being able to exist and operate thanks to the 'feeding' energy of Wralda's spirit.“This is our primal history:
Wralda, who is wholly good and eternal, created the potential. From this came time, and time wrought all things; even the very Earth herself. -2b Primal History”
When first reading the OL Kroder may seem insignificant due to his name being relegated to a few lines, however his importance cosmologically and historically cannot be overstated. At some point it became common in Finda cultures to begin to worship Kroder as their chief god. Perhaps this was due to a weakening or disconnect with Wralda's spirit, they could only see the material and began to worship it, lacking the bigger picture. Kroder became the ancient gods Krodo, Chronos, Crom Cruach, Saturn, Shamash, etc. Those familiar with gnosticism of any strain will recognize the connection between the god Saturn and the demiurge.
Although worship of Kroder is false and has introduced so many evils into the world, I am not positing that Kroder as an entity is evil, instead cultures have projected ideas onto it - creating an image that doesn't exist in reality. Kroder is time, a force of nature. However we do know from lived experience that the world is full of suffering. Cultures that worship the demiurge cannot wrap their heads around 'the Problem of Evil' to this day, however our Nyhellenia was able to solve this question succinctly in the second millennium bc.
This is gnostic doctrine in a quote. The world is cruel, and ruled by time. Fate is the causality of time. To remedy this, we must search within ourselves, becoming strong and wise. How do we do this?“No,” said Minerva. “But I do not know any gods who do evil. Therefore, I cannot entreat them to become better. I know only one ‘God’ — that is Wralda’s spirit. And because ‘God’ means ‘good’, he also does no evil.”
“Where, then, does evil come from?” the priests asked.
“All of the evil comes from yourselves and from the stupidity of the people who walk willingly into your trap.”
“If, then, your supreme being is so very good, why does he not prevent evil?” the priests asked.
Hellenia answered: “Frya has put us  on the path, and the Bearer — that is time — must do the rest. For all calamities, counsel and help can be found. But Wralda wants us to search for them ourselves, in order that we should become strong and wise. If we refuse, he permits our fate to unravel, so that we should experience the results of wise and foolish deeds.” - 4f 'Minerva'
Point two, Frya's Tex as a manual for gnosis. It lets us know when it is appropriate to turn to Wralda and when we must help ourselves, how slavery destroys any chance of gnosis, and why we cannot mix blood. Frya's blood is imbued with Wralda's spirit, meaning that descendants of Frya are more inclined to reach gnosis.
Wralda deserves our eternal gratitude for imbuing our ancestors so deeply with his spirit. -06, Yule, Script, Numbers
Frya's warning is not only to prevent foreign customs from being adopted, but also to cultivate a gnostic civilization.Hail to all children of Frya who love that which is good! Through them, bliss shall come to Earth. - 13 Primal Teachings
Bringing the previous discussion of the afterlife into this post, we've established there is a system of reincarnation and periods between lives however. It is implied through the line,
that those who achieve gnosis earn a spot with Frya and her maidens, potentially on the 'Watch-star' as a guiding spirit of the folk. There is an ancient Germanic idea of reincarnating within your lineage, which I think comes from this. Mixing would mean in your next life, you would have even less of a chance of gnosis, or perhaps even sever your ability to reincarnate to some degree. (This is not to say gnosis is exclusive to Fryas, see: Yesus/Jessos)"In the end, they shall see me again. But only those can I deem free who are slave neither to another nor to their own passions."
This is why also it is so important we throw out Christianity. As of now nearly the entire world worships the demiurge. They worship a god who demands slavery, sacrifice, submission, and subjugation. This system of slave morality has cut off so many from achieving gnosis. Christians believe the great evil in our world today stems from satan and those who worship him. In reality those attempting to reset the world, remake it in their image, and destroy the light of Frya worship the same god they do -Saturn. A lot more can be said on this topic alone, however I think this is a good stopping point and opens up this discussion.
Chronos as depicted in Mithraism