See the Council of Florence for a clear picture of what we disagree about, and why we do.
The main issues that have separated us are:
- The doctrine of the "filioque." The Catholics believe the Holy Spirit proceeds from the Father and the Son, the Orthodox believe the Holy Spirit proceeds from the Father alone.
- The legitimacy of the "filioque" phrase that was interpolated in the Nicene-Constantinopolitan Creed in the first place. The Catholics believe that the ecumenical councils did not forbid any such clarifications to be added to the creed, and the Pope has the right to add something to the creed without calling for an ecumenical council if it becomes needed to fight heresy. The Orthodox believe that the Council of Ephesus and the council at Constantinople in 879-880 forbid anyone, even another council, from adding words to the creed as defined at the 1st Council of Constantinople.
- The use of unleavened bread for the Eucharist. Catholics believe that unleavened bread can be used. Orthodox believe that it must not be used, and that leavened bread alone is supposed to be used.
- Purgatory. Catholics believe in three states for the soul before the final judgment: Heaven, Hell, and Purgatory; Heaven for the saved, Hell for the damned, temporary Purgatory for those who will be saved but did not die purified of sin, and the prayers of the Mass are for those who are in Purgatory to make their purgation quicker and less painful. Orthodox believe in two states only: Heaven and Hell; and the prayers of the Liturgy are for those who are in Heaven so that they could enjoy better bliss, and for those who are in Hell so that they could suffer lesser torment, to the point they might even be saved.
- Papal primacy. Catholics believe that the primacy of the Pope is to be a form of "supremacy" according to which the Pope is fundamentally and always the head of the Church, he has universal jurisdiction, he can define dogma infallibly when doing so with the intent of fulfilling his office as teacher of the whole Church, and he inherits this apostolic role from Peter; as a result, the Church of Rome fundamentally cannot fall into heresy. Orthodox believe that the primacy of the Pope is to be a form of "first among equals" according to which the Pope, being Patriarch of Rome, is no different from any other patriarch, and indeed from any other bishop, and Peter's special mission extends to all bishops; as a result, the Church of Rome can fall into heresy (and, since the 11th century, has been in heresy).
These are the historical doctrinal disputes. For recent ecumenical outlooks on these, and on what we can agree and disagree on today, see:
http://www.vatican.va/roman_curia/pontifical_councils/chrstuni/sub-index/index_orthodox-ch.htm
http://www.assemblyofbishops.org/ministries/dialogue/orthodox-catholic/
For the actual schism itself:
It happened over a long period.
The break between Rome and Constantinople: the two bishops broke communion with each other in 1009 for unknown reasons. In 1452, communion between Rome and Constantinople resumed, based on the decrees of the Council of Florence. In 1484, communion officially ended again, although in practice, it had ended also in 1452, after the fall of Constantinople.
The break between Rome and Alexandria: The bishop of Alexandria excommunicated the bishop of Rome in 1204 due to the sack of Constantinople.
The break between Rome and Antioch: AFAIK, we're not sure when exactly Antioch broke communion with Rome. It is thought that Antioch remained in communion with Rome and with Constantinople even if commemoration ceased, but commemoration of the Pope resumed with Jesuit evangelization in the 16th century, until the Melkite schism in 1729 in which the pro-Catholic party broke communion with Constantinople, Alexandria, and Jerusalem, and the pro-Orthodox party broke communion with Rome.
The break between Rome and Jerusalem: The bishop of Jerusalem excommunicated the bishop of Rome in 1204 due to the sack of Constantinople.
>>581313
If we anathematized the Immaculate Conception, two of the three saints who are called "Pillars of Orthodoxy" (St. Gregory Palamas and St. Mark of Ephesus) wouldn't unapologetically support it.
We're more bothered by it being made a dogma necessary for salvation.
>>581314
>NFP is not contraception
lol
You don't get to say "all contraception is bad" then define for yourself what counts as "contraception."
Many of the saints who are cited by Catholics to defend equating the sin of Onan with murder also saw NFP as being equal to murder, you know.
Do not fool anybody - natural law theory is the main reason that the use of "artificial" contraception is a mortal sin when "natural" contraception isn't.