The Forge of God begins with several strange events taking place : the disappearance of one of Jupiter's moons, the sudden appearance of here-to unknown mountains in Death Valley and Australia the encounter with alien emissaries bringing conflicting messages. The Australian aliens promise a new era of peace and prosperity, while the American envoy bears news of the impending destruction of Earth.
Bear describes mankind's reaction to certain destruction at the hands of godlike forces with a clinical detachment. Characterization is definitely not his forte, but Bear's imagination is better geared to new (or not so new) concepts, like beserkers, the Law or his frightening world-killing weaponry.
All in all, an interesting read, though the sequel, Anvil of Stars, is definitely more interesting.