jdudan54: many in this world -- religious and non-religious alike! -- don't see a small piece of bread sopped in wine as a Man's (or even a man's) body and blood; it's bread and wine to them, and we're just being silly and literalist. To many confessions of Christianity, the idea that this could be a vital part of our healing and salvation is convoluted and an unnecessary addition by man, post-Scripture.
To add to the things already mentioned in this thread, some Scriptures that the Orthodox see as pointing to a continuation of the guiding and preserving presence of the Holy Spirit of and within the Church are the following:
John 16:13 quotes Christ as saying that the Holy Spirit shall guide all of the disciples into all truth. So at least there's a good start to the Church.
Matt. 16:18 (very well known in conversations like this w/both RCs and Orthodox) says that God will not allow the gates of hell to prevail against the Church. Question: if the entire Church embraces a false doctrine, is this not Satan prevailing against the entire Church? We in the catholic traditions that claim apostolic succession would say so.
John 17:20-1 is part of Christ's beautiful high priestly prayer that says that the prayer for unity and oneness with God that the Church is to experience is not reserved for the Apostles alone, but also for those who would "believe...through their word."
2 Thess. 3:6 moves us away from quotes from the Lord and gives us the words of the blessed St. Paul, who warns the Thessalonians to withdraw from all who do not keep the traditions that were received from "us," meaning from him and the other Apostles.
2 John 10 says that, for example, if someone were to come and not preach the apostolic doctrine of Christ's coming in the flesh, we were not to receive him.
2 Tim. 2:2 says that St. Timothy, who received the grace of the priesthood (though the word priesthood is not used, admittedly) through the laying on of hands*, was to train and appoint men in the teachings of St. Paul -- men who would then in turn train others in the same. The assumption of apostolic succession in doctrine is seen clearly here.
Acts 15 -- the Council at Jerusalem, at which were present not only the Apostles, but also many whom they had appointed, was considered binding on all Christians re: the entry of many Gentiles into the Church. The inclusion of others in the safeguarding of the Church and guiding of the same in all truth had already begun.
2 Thess. 2 -- not only does this contain the famous "hold to our traditions, whether by word or by epistle verse" that favors oral and written tradition together, but the entire chapter contrasts those who would keep these doctrines pure against those who would be deceived and fall away. Many would be so deceived and fall away, St. Paul said, but the faithful would remain, the Church would continue to exist. Question: if there is no record of anyone ever
contesting apostolic succession who still exist today (before the Waldensians in Italy many centuries later, that is), could it not be reasonable to conclude that this doctrine was assumed and taught by the Apostles?
*1 Tim 1:14 and 2 Tim. 1:6 are both verses that mention the laying on of hands of the eldership as the method by which "the gift" was given to St. Timothy. We see (and, as Paradosis' link
shows, the early Church Fathers confirm) this to be the grace of the priesthood in order to baptize, to celebrate the eucharist, to formally anoint the sick for healing...in short, to administer the sacraments of the Church.
Again, as anastasios has said, this anointing and appointing of other elders by the Apostles, as well as by those who were appointed by said Apostles, was considered just as vital as the doctrine itself; the faithful were not to admit or have fellowship with those who were from outside this fold. This was the intention of the Apostles. Whether the Apostles thought that God could appoint someone through supernatural means other than physically through the Apostles is immaterial (this certainly could happen, and did initially in the case of St. Paul, who nevertheless eventually was given the "right hand of fellowship" into the Apostles' fold). The understanding in the early Church was that the Apostles would appoint leaders, who would then in turn appoint leaders, etc., through the laying on of hands and a common confession of faith, and the preservation of the Church through the grace of the Holy Spirit would continue on, and the gates of hell would not prevail against Her.
We see this as Scripture's clear testimony, kept even to this day.
Hope this has helped.