The center of the Faith, as we know from Scripture and from 1,500 years of Church history (i.e., until things changed during the Reformation for some Western Christians), is the Eucharist. All Christians gather together around the Body and Blood of Christ. The Liturgy revolves around it.
The Eucharist is where our “eyes are opened” in the “breaking of the bread,” (Luke 24) for “unless you eat the flesh of the Son of Man and drink his blood, you have no life in you. Whoever feeds on my flesh and drinks my blood has eternal life, and I will raise him up on the last day. For my flesh is true food, and my blood is true drink” (John 6).
That is why all the fathers of the Church, the very disciples of the apostles, emphasized it as such. For example, St. Ignatius of Antioch (AD 50 – AD 117), a disciple of the apostles Peter and Paul, wrote to the church in Smyrna:
Consider those who are of a different opinion from us, as to what concerns the grace of Jesus Christ which is come unto us, how contrary they are to the design of God. They have no regard to charity, no care of the widow, the fatherless, and the oppressed; of the bond or free, of the hungry or thirsty.
They abstain from the Eucharist, and from the public offices; because they confess not the Eucharist to be the flesh of our Savior Jesus Christ which suffered for our sins, and which the Father of his goodness raised again from the dead. And for this cause contradicting the gift of God, they die in their disputes; but much better would it be for them to receive it, that the might one day rise through it. (To the Smyrnaeans, 2:14-17)
St Justin Martyr, writing in 150AD with the first description of what was going on in the Christian Liturgy, wrote:
And this food is called among us the Eucharist, of which no one is allowed to partake but the man who believes that the things which we teach are true, and who has been washed with the washing that is for the remission of sins, and unto regeneration, and who is so living as Christ has enjoined.
For not as common bread and common drink do we receive these; but in like manner as Jesus Christ our Savior, having been made flesh by the Word of God, had both flesh and blood for our salvation, so likewise have we been taught that the food which is blessed by the prayer of His word, and from which our blood and flesh by transmutation are nourished, is the flesh and blood of that Jesus who was made flesh. (First Apology, chapter 66)
There are many other passages of many fathers speaking similarly. Also, the Eucharist is not only the very Flesh and Blood of Christ, but it also depends on apostolic succession. The early Church emphasized that because of the sects (gnostic, arian, apollinarian, eutychian, etc.) one could not take upon himself to celebrate the Eucharist without the authority of a bishop who had been in the ordination line of the apostles (and thus holding the apostolic doctrine and faith).
So again, St Ignatius wrote,
Make certain, therefore, that you all observe one common Eucharist; for there is but one body of our Lord Jesus Christ, and but one cup of union with his blood, and one single altar of sacrifice–even as there is also but one bishop, with his clergy and my own fellow servitors, the deacons. This will ensure that all your doings are in full accord with the will of God.” (Letter o the Philadelphians, chapter 4)
“Wherever the bishop appears, there let the people be; as wherever Jesus Christ is, there is the Catholic Church. It is not lawful to baptize or give communion without the consent of the bishop. On the other hand, whatever has his approval is pleasing to God. Thus, whatever is done will be safe and valid. (Letter to the Smyrnaeans, chapter 8)
Notice that these are from the earliest Christian writings available to us. These were second generation disciples of the apostles. There are many other passages like this as well in the Fathers.
So now we have 2 things that are necessary for the fullness of the Christian life, and certainly for the apostolic liturgy and worship: the Eucharist, and apostolic succession which makes it real and safeguards the organic unity of the Church. Those two things alone exclude Protestantism.
How about about sola scriptura? As I have said elsewhere, sola scriptura does not mean that one goes only to the Bible for doctrine (the magisterial Reformers – Luther and Calvin – understood that; this misunderstanding is not what they meant by the term, since they themselves tried to support their claims from historical interpretations of the Church, even though they were not able to do that very well in my opinion).
Properly understood, sola scriptura means that the ultimate authority on the matters of doctrine and piety are the Scriptures. Which does not mean at all that the Scriptures contain all truths, much less that truth is restricted to Scripture.
Of course, even a proper understanding of sola scriptura has its own problems. As Luther and Calvin understood, the ultimate authority on the matters of doctrine and piety are the Scriptures properly interpreted – whether the final authority of interpretation will be the Roman Catholic Magisterium, Luther, Calvin, the Westminster Confession and Catechisms, the Belgic Confession and the Heidelberg Catechism, Pastor Bob, Me Myself and I, Benny Hinn, Tim LaHaye, Oprah, and so on. There are thousands of Protestant denominations which agree on a number of issues, and yet disagree on others which they consider important enough to have left and begun a new church.
Or, the final authority of interpretation will be the ongoing living tradition of the Church (including the Fathers, the Ecumenical Councils and present day canonical bishops).
In other words, sola scriptura does not work because if one says the Bible is the final authority, such authority can only be applied by interpreting the Bible, and so the real final authority will be the one who determines what the Bible means. And, of course, claiming the Spirit as the one who does that for each believer does not work; for every 3 “Spirit filled” believers, one finds at least 5 contradictory Christian doctrines from interpreting the Bible differently.
That is not even to mention that Protestants who adhere to sola scriptura cannot use the concept of “Bible” legitimately, because the New Testament, which most Christians did not have for centuries, was defined and canonized by the Church, not by the Bible. The Church said that the Didache was not the New Testament, and the letter to the Ephesians was, and so on. The final authority for one to even consider a writing to be the “Bible” comes from the Church, not from the Bible. It was the Church who wrote the Bible, and then said that the Bible is the Bible. After all, as St Paul told his pupil Timothy,
I write so that you may know how you ought to conduct yourself in the house of God, which is the Church of the living God, the pillar and ground of the truth. (1Tim. 3:15)
What about icons? Yes, through them we do talk to those whom they represent, and ask for their prayers. It was the pagans of old that denied that there is eternal, everlasting life with God after death. But Christianity affirmed that Christ was “risen from the dead, trampling down death by death, and bestowing life upon those in the tombs.” He is “ not God of the dead, but of the living” (Luke 20).
Those who live their lives following him serve him by loving and serving others. Whey they “repose” (as we call it), they become even more alive to God, without the encumbrances of sin, weaknesses, body limitations of tiredness, hunger, need of sleep, etc. They behold the face of God in Christ, and, filled with his Spirit, transfigured by grace and deified in the presence of the living God, they continue to worship and serve him more than ever – which means they continue to love and pray for those who seek their assistance. They are able to do that because they are united to Christ by the Spirit, not dependent on spatio-temporal considerations of time, place, ability to know by the physical senses, etc.
Just like we instinctively ask for the prayers of those whom we know to be devout people here on earth – people that we trust, that we know that they know God, and that God hears their prayers because they walk with him (of which the Scriptures are full of examples, the prophets being the most common) – so we also ask for the prayers of those who are alive in Christ. We often use the word “pray” to them, because the English word means to ask for something, not to worship.
So icons are windows of heaven. Against the gnostics (forms of which Protestantism is full, unfortunately), the Church has always affirmed that God created and redeemed both spiritual things and material things. He sanctifies matter for his own use. Icons become blessed elements through which we address God, his Mother, and his saints, much like we look at a picture of a loved one and kiss it, or have a thought about them, or say a prayer for them.
For more on icons, see my post “Worshipping Images? Iconoclasm and the 7th Ecumenical Council.”