Original sentence: The New Catholic Encyclopedia for example says, "The doctrine of the Holy Trinity is not taught in the Old Testament", and The Columbia Electronic Encyclopedia adds, "The doctrine is not explicitly taught in the New Testament", although these sources strongly assert that the doctrine is implicit
Edited sentence: " - although these sources strongly assert that the doctrine is implicit.The New Catholic Encyclopedia says, "The doctrine of the Holy Trinity is not taught in the Old Testament" and The Columbia Electronic Encyclopedia adds, "The doctrine is not explicitly taught in the New Testament