There seems to be a common assumption in an awful lot of modern theology that the primary truth about God is that he is love. "God is love" is at least Biblical as a statement (1 John 4:8, 16), and there's a lot of important stuff that can be said about the Trinity from that statement.
But of course, people often load the word "love" with a lot of baggage it wasn't meant to carry, and interpret "God is love" in a way that contradicts large chunks of the rest of the Bible.
But why should "God is love" be primary at all? Why not "God is light; in him there is no darkness at all." (1 John 1:5). After all, it's in the same book. But I don't think either "God is love" or "God is light" is the number one candidate for a three word description beginning "God is...". Nor is "Truth", "Life" or "Wisdom", though there may be something to be said for each of those.
I think there are two possibilities much stronger than either. After all, we're never told that "God is love, love, love", but we are told that he is "holy, holy, holy." Actually, we're told that as many times as we are told that God is love (Isaiah 6:3, Rev 4:8), and we're told that God is holy quite a lot more (Lev 11:44, Lev 11:45; Josh 24:19; 1 Sam 6:20; Ps 22:3; 99:9; Isaiah 5:16; 1 Pe 1:16 for starters). So I'd say "God is holy" is much closer to being his primary attribute that "God is love" on the basis of the Biblical evidence.
The other possibility of course is "God is Jesus".
Now imagine what modern theology would be like if we started with the truth that God is holy rather than the truth that he is love.