Some of Gregory's theological writings suggest that, like his friend Gregory of Nyssa, he may have supported some form of the doctrine of apocatastasis, the belief that God will bring all of creation into harmony with the Kingdom of Heaven. This led some late-nineteenth century Christian universalists, notably J. W. Hanson and Philip Schaff, to describe Gregory's theology as universalist. This view of Gregory is also held by some modern theologians such as John Sachs, who said that Gregory had "leanings" toward apocatastasis, but in a "cautious, undogmatic" way. However, it is not clear or universally accepted that Gregory held to the doctrine of apocatastasis.