Athanasius versus the Arians

This is an excerpt from Philip Schaff's History of the Christian Church Vol. III, and deals with the differences between Athanasius and those who supported him with the Arians.

Arianism was a religious political war against the spirit of the Christian revelation by the spirit of the world, which, after having persecuted the church three hundred years from without, sought under the Christian name to reduce her by degrading Christ to the category of the temporal and the created, and Christianity to the level of natural religion. It substituted for a truly divine Redeemer, a created demigod, an elevated Hercules. Arianism proceeded from human reason, Athanasianism from divine revelation; and each used the other source of knowledge as a subordinate and tributary factor. The former was deistic and rationalistic, the latter theistic and supernaturalistic, in spirit and effect. The one made reasonableness, the other agreement with Scripture, the criterion of truth...

In close connection with this stood another distinction. Arianism associated itself with the secular political power and the court party; it represented the imperio-papal principle, and the time of its prevalence under Constantius was an uninterrupted season of the most arbitrary and violent encroachments of the state upon the rights of the church. Athanasius, on the contrary, who was so often deposed by the emperor, and who uttered himself so boldly respecting Constantius, is the personal representative not only of orthodoxy, but also of the independence of the church with reference to the secular power...

While Arianism bent to the changing politics of the court party, and fell into diverse schools and sects the moment it lost the imperial support, the Nicene faith, like its great champion Athanasius, remained under all outward changes of fortune true to itself, and made its mighty advance only by legitimate growth outward from within. Athanasius makes no distinction at all between the various shades of Arians and Semi-Arians, but throws them all into the same category of enemies of the catholic faith. [source]