Macedonius I of Constantinople, a heretic, was the bishop of Constantinople during the mid-fourth century. He was an Arian, and with the support of Emperor Constantius II, the Semi-Arian party was able to install him as the bishop of Constantinople. He served as bishop for two periods: from 342 to 349 and from 351 to 360.
Little is known of the life of Macedonius before he became a candidate for bishop of Constantinople after Bp. Alexander died in 336. At that time he was supported by Arians against the Orthodox Bishop Paul who had succeeded Alexander. After the death of his father, Constantine I, in 337, Emperor Constantius II arrived in Constantinople in 339 and convened a council of Arian bishops that exiled Paul and moved Eusebius of Nicomedia to the see of Constantinople, disappointing Macedonius.
After the death of Eusebius in 341, the contest between the supporters of Paul and Macedonius arose again with each side, in 342, independently installing their candidate as bishop of Constantinople. Constantius, however, sent his general Hermogenes to evict Paul. This ended in a riot during which Hermogenes was killed. In response, Constantius removed Paul again, and rebuked Macedonius for allowing himself to being consecrated without imperial approval. However, Constantius allowed him to continue to serve at the church in which he was consecrated. Rejecting letters of support from Pope Julius I, Constantius reinstated Macedonius as bishop of Constantinople, but not without bloodshed. 
Macedonius remained bishop of Constantinople for about five years while Constantius and the Arians' treatment of Paul and Athanasius was disputed. In 346, under threats by his brother Constans, emperor of the West and a supporter of the Orthodox, Constantius reinstated Paul to the see of Constantinople. Macedonius retired to his church in Constantinople. In 350, Constans was murdered. This resulted in Constantius regaining control of the eastern empire. In 351, with Constantius in control, Paul was once again exiled and, through imperial edicts that followed his departure, allowed the Arians to gain dominance in the church of Constantinople including return Macedonius to the see of Constantinople.
What followed is best described by Socrates Scholasticus: "The exploits of Macedonius on behalf of Christianity, consisted of murders, battles, incarcerations, and civil wars." 
Macedonius' favored status under Constantius came to an end in 358 when he moved the body of Constantine I from its crumbling sepulchre without consulting the emperor. The translation of Constantine's remains to the church of Acacius the Martyr resulted in an uproar from the Orthodox who assailed as sacrilege "the disinterment of the supporter of the Nicene faith."
When Macedonius appeared at the Council of Seleucia in 359, the council ruled that since he was under accusation, it was not proper for him remain at the council.  Later in 360, his opponents, who included Acacius, Eudoxius, and other Arians, followed Macedonius to Constantinople where they took advantage of Constantius' indignation toward Macedonius following his mishandling the translation of Constantine's body and deposed him on the grounds of cruelty and canonical irregularities. With his deposition, Macedonius retired to a suburb of Constantinople where he died, probably about 364.
While he was a member of the Semi-Arian party, Macedonius came to support a view that while it generally supported the Nicene-Constantinopolitan Creed|Nicene]] creed rejected the Divinity of the Holy Spirit. The doctrine developed into a sect that after his death carried his name: Macedonians. The sect was also referred to as the Pneumatomachi.
- ↑ Socrates Scholasticus, H. E. ii. 16
- ↑ Socrates Scholasticus, H. E. ii. 38
- ↑ Socrates Scholasticus, H. E. ii. 40
|Bishop of Constantinople|
|Bishop of Constainople|
Eudoxius of Antoch