<P> The doctrine of the Trinity , considered the core of Christian theology by Trinitarians , is the result of continuous exploration by the church of the biblical data , thrashed out in debate and treatises , eventually formulated at the First Council of Nicaea in AD 325 in a way they believe is consistent with the biblical witness , and further refined in later councils and writings . The most widely recognized Biblical foundations for the doctrine 's formulation are in the Gospel of John . </P>
which aspect of the roman catholic church established in the 300s remains today quizlet
The doctrine of the Trinity