Eusebius of Nicomedia (/juːˈsiːbiəs/; Ancient Greek: Εὐσέβιος; died 341) was an Arian priest who baptised Constantine the Great on his deathbed in 337.
[11] He afterward modified his ideas somewhat, or perhaps he only yielded to the pressure of circumstances; but he was, if not the teacher, at all events the leader and organizer of the Arian council.
At the First Council of Nicaea in 325, he signed the Confession, but only after a long and desperate opposition in which he was said to "subscribe with hand only, not heart"[12] according to ancient sources.
[14] After the lapse of three years, he succeeded in regaining the imperial favor by convincing Constantine that Arius and his views do not conflict with the proclaimed Nicene Creed.
Upon his return, he regained the lost ground resulting from the First Council of Nicaea, established alliances with other groups such as the Melitians and expelled many opponents.
He was able to dislodge and exile three key opponents who espoused the First Council of Nicaea: Eustathius of Antioch in 330, Athanasius of Alexandria in 335 and Marcellus of Ancyra in 336.
[20] It was because of Eusebius that "On the whole, Constantine and his successors made life pretty miserable for Church leaders committed to the Nicene decision and its Trinitarian formula".