GreekOrthodox, years ago, I earned my first degree at a two-year, quintessentially American, career-oriented college, where education was a means, not an end. Nobody saw the wide, systematic perspective that kind of education would have given us.
St. Thomas's thought is systematic enough that it's hard to write a book about any one aspect of it. To understand his metaphysics, say, you need to interpret it with plenty of context because it relates intimately to many, many other parts of his thought.
Larson seems to have torn some Eastern Orthodox thought from a huge context. During a lecture about the Emergent Church movement, a very dangerous movement, I think, Dr. D.A. Carson convinced me that, although everybody sees the world some perspective or other, we can know how things actually are in the world. We can have justified true beliefs that conform to reality. But we can't see anything from God's perspective, because He's all-knowing and we're not that way. For St. Thomas, we can get genuine knowledge about God and His eternality. The trouble is that, He differs radically enough from us that we need to know analogically about Him when we know anything about Him. You shouldn't sum up something in a paragraph when you need a whole article just to try to scratch the tiniest part of the surface. Larson has been missing the Eastern Orthodox forest because he's been staring at a baby termite on a seedling.
What do you mean by "schism?" For a Catholic, a schismatic is one who rejects the papacy in itself and a heretic is someone who denies a dogma or doubts it obstinately. From our perspective the Eastern Orthodox are in both heresy and schism, in heresy because they reject papal infallibility and in schism because they reject papal primacy. For us, the Pope is not the first among equals. We believe that he's the visible head of the only Church that Christ founded. He's also a monarch like the vice-president of a company where Christ is the president. The rites in the Catholic Church, Roman, Ukrainian, Maronite, and so forth are parts of the one Church, not autocephalus Churches.
In Thomistic thought, by the way, "eternity" and "timelessness" seem to be synonyms of each other. Someone timeless is unchanging, unchangeable, and simple, where being simple means having no parts of any kind.