Nichiren may indeed have included the three major forms of Western monotheism if he had known about them, as he seems to have wanted to account for all the major religions in the world. I also believe that he would have evaluated them using the same method of comparison in terms of the scope of time scales. To review: just as the Buddha criticized the sixty-two (or ninety-five) views of his contemporaries who drew dogmatic conclusions about the nature of life based on limited experiences either in this life or even from past-life recall, Nichiren evaluated Confucianism, Taoism, Brahmanism, Buddhism, and other philosophies and religions based on how limited or vast a scope of time their teachings accounted for. Confucianism fares the worst for not even attempting to account for life before birth or after death but limiting itself to teaching morality only in terms of the present lifetime.

Brahmanism fares better for it does teach that there is a cycle of rebirth that unfolds according to the law of karma, and thus accounts for a much greater scope of time. In fact, Brahman cosmology teaches that there are whole cycles wherein world systems are created, maintained, and then destroyed over the course of eons and within those cycles beings are reborn continually until they can attain one of the heavenly realms. The Upanishads taught that those who realized the Ātman or True Self would be forever liberated from these cycles, but the Buddhist sūtras do not mention the Upanishads nor does Nichiren.

From the Buddhist point of view, however, in the course of time even those reborn in the heavens will exhaust their merit and they will have to be reborn elsewhere depending on what causes are able to come into fruition. From the Buddhist perspective even the vast amounts of time spent in a hell-realm or a heavenly-realm is still a finite period of time because all caused and conditioned states will eventually come to an end. Such is the universal law of the impermanence of all conditioned phenomena.

Coming back to Western monotheism, … The important thing is that the mainstream view posits only one lifetime to be followed by an eternal afterlife of some sort. Going by Nichiren’s criteria, I think he would perhaps have placed Western monotheism ahead of the agnostic Chinese schools of thought because it at least provides for some kind of afterlife wherein the causes one makes in this life will come to fruition for good or for ill. On the other hand, I think he would not have put Western monotheism on the level of Brahmanism, as the latter accounts for many lifetimes and its understanding of the unfolding of cause and effect over many lifetimes is more developed. From a Brahmanist point of view, one might live in heaven or hell for thousands or millions of years, but it is not actually an eternity though mistaken as such by those who don’t see larger time scale. I stress, again, that this is my guess based on how Nichiren evaluated the other non-Buddhist traditions.

As far as Nichiren and his contemporaries were concerned, these myriad views of causality held by the non-Buddhists of India all boiled down to the following three views: (1) the effect can be found within the cause, (2) the effect cannot be found within the cause, and (3) the effect does and does not exist within the cause. These views concerning causality are important because they are denials of the law of cause and effect as taught by the Buddha, and the law of cause and effect taught by the Buddha relates to right view and right practice that leads to awakening.
In the Outline of All the Holy Teachings of the Buddha (Ichidai Shōgyō Tai-i), Nichiren associates Kapila with the view that effects are the transformations of the cause that is their substance or self-nature. This is justified in that Sāmkhya teaches that an effect exists as a potential within a cause and is produced when the cause transforms itself. For example, it is like clay (the cause) being shaped into a jar (the effect). The clay remains clay, though it has become a jar. In this view nothing is ever really created or destroyed, there are only transformations of what has always and will always exist. Cause and effect are identified as simply two different modes of an eternal unchanging substance. This is the view that Buddhism calls “eternalism.”

Uluka is associated with the view that effects are generated by external causes. This is justified in that the Vaiśeshika held that the cause gives rise to the effect; but the cause does not enter into the being of the effect. The effect then becomes a cause for something else and in turn passes away. For example, once the moist lump of clay has been shaped by the potter and fired in the kiln it is no longer clay but a jar. In this view the cause disappears when the effect comes into existence and the effect itself disappears when it becomes the cause for some other effect. Cause and effect are denied any underlying substantial identity as the former vanishes without a trace when the latter comes into being. Buddhism calls this view “annihilationism.”

Rishabha is associated with the view that effects are the product of causes external and internal to them. This is consistent with the Jain teaching of relativity in respect to conceptual statements. In other words, one should grant the relative truth of a variety of positions if one is not to fall into one-sided or partial views. Due to their teaching of relativity, the Buddhists attributed to Rishabha the position that a cause may in some respects transform into its effect but in other respects the cause and effect are distinct entities. Using the example of clay being turned into a jar: in some respects, the clay remains as the basis of the jar, but in other respects the jar has qualities the lump of clay did not have in terms of its shape, firmness, and ability to function as a container. Cause and effect are thereby identical in terms of some qualities but separate entities in terms of others.

Finally, the materialists are associated with the view that chance or fate governs the appearance and disappearance of phenomena and that there are no causal relations, that is to say no causes or effects. This is the view that things just happen without any rhyme or reason.

The Ichidai Shōgyō Tai-i passage that aligns the thinkers of India in terms of four alternatives uses the tetralemma, a Buddhist way of presenting two alternatives, their combination, and the negation of both alternatives. The tetralemma supposedly exhausts all the possible solutions to a question. The present tetralemma about the relationship between cause and effect is often taken in Buddhism to really be about the relationship between the one who acts and the one who experiences the karmic fruition of that act either within the same lifetime or in some future lifetime. In other words, is the person who makes the cause the same as the person who will experience the effect? Kapila would say yes, Uluka would say no, Rishabha would say that both Kapila and Uluka are correct in some sense, and the materialists would deny any kind of causal connection. All four alternatives, however, contain an assumption that the Buddha did not share: that causes and effects are substantial entities that do or do not endure through time. Furthermore, the Buddha denied that there is an unchanging, independent, “self” that performs causes and suffers effects. Without that assumption, none of the proposals makes any sense.