Complex sentence: Berengar's position was never diametrically opposed to that of his critics, and he was probably never excommunicated, but the controversy that he aroused forced people to clarify the doctrine of the Eucharist.
Split into simpler sentences: Berengar's position was never diametrically opposed to that of his critics, and he was probably never excommunicated. But the controversy that he aroused forced people to clarify the doctrine of the Eucharist.