Bultmann is much maligned for reducing Theology to anthropology. Which is worrying because I find him hard to disagree with about this issue. I think the key text in which he does this is in his Theology of the New Testament, vol 1, p190-191.
Of course he is not really "reducing" theology to anthropology but arguing that meaningful theology is anthropological, and therefore does not just say something about God in the abstract but also realtes it to human reality and human response. I'm sure Bultmann had his sins, but I'm not sure this is one of them.
. . . Pauline theology is not a speculative system. It deals with God not as He is in Himself but only with God as He is significant for man, for man’s responsibility and man’s salvation. Correspondingly, it does not deal with the world and man as they are in themselves, but constantly sees the world and man in their relation to God. Every assertion about God is simultaneously an assertion about man and vice versa. For this reason and in this sense Paul’s theology is, at the same time, anthropology. But since God’s relation to the world and man is not regarded by Paul as a cosmic process oscillating in eternally even rhythm, but is regarded as constituted by God’s acting in history and by man’s reaction to God’s doing, therefore every assertion about God speaks of what He does with man and what He demands of him. And, the other way around, every assertion about man speaks of God’s deed and demand — or about man as he is qualified by the divine deed and demand and by his attitude toward them. The christology of Paul likewise is governed by this point of view. In it, Paul does not speculatively discuss the metaphysical essence of Christ, or his relation to God, or his “natures,” but speaks of him as the one through whom God is working for the salvation of the world and man. Thus, every assertion about Christ is also an assertion about man and vice versa; and Paul’s christology is simultaneously soteriology.