How quickly did error seek to enter the Church? In his History of the Christian Church, Eusebius refers to a now non-existent writing of Hegesippus. Hegesippus seems to have described what happened when the Apostles died:
“In describing the situation at that time Hegesippus goes on to say that until then the Church has remained a virgin, pure and uncorrupted since those who were trying to corrupt the wholesome standard of the saving message, if such there were, lurked somewhere under cover of darkness. But when the sacred band of the apostles had in various way reached the end of their life, and the generation of those privileged to listen with their own ears to the divine wisdom had passed on, then godless error began to take shape, though the deceit of false teachers, who now that none of the apostles was left threw off the mask and attempted to counter the preaching of the truth by preaching the knowledge falsely so called.” [Source: Eusebius, The History of the Christian Church From Christ To Constantine (Minneapolis: Augsburg Publishing House, 1975), 143 (online link to this section)].
But from the beginning, it appears error was always at the doorstep of the Church, waiting to come in:
2 Corinthians 11:13-15 (False apostles claiming apostolic ties)
For such are false apostles, deceitful workers, transforming themselves into apostles of Christ. And no wonder! For Satan himself transforms himself into an angel of light. Therefore it is no great thing if his ministers also transform themselves into ministers of righteousness, whose end will be according to their works.
Acts 20: 28-31 (Paul warns of those false teachers immediately coming into the church after his departure)
“For I know this, that after my departure savage wolves will come in among you, not sparing the flock. “Also from among yourselves men will rise up, speaking perverse things, to draw away the disciples after themselves. “Therefore watch, and remember that for three years I did not cease to warn everyone night and day with tears."
Galatians 1:8-9 (Even genuine apostles may be prone to error)
But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed. As we have said before, so now I say again, if anyone preaches any other gospel to you than what you have received, let him be accursed.
The apostle Peter himself falls into error concerning the gospel:
But when I saw that they were not straightforward about the truth of the gospel, I said to Peter before them all, “If you, being a Jew, live in the manner of Gentiles and not as the Jews, why do you compel Gentiles to live as Jews? (Galatians 2:14)
The Churches Mentioned in Revelation:
The Church of Pergamos: there were those who had absorbed the doctrine of Balaam, and the doctrine of the Nicolaitans (Rev. 2:14, 15).
The Church of Thyatira: Allowed the prophetess Jezebel 'to teach and seduce My servants to commit sexual immorality and eat things sacrificed to idols' (Rev. 2:20).
The Church of Sardis: Christ declares them “dead.” Only a few people “remembered what they received and heard and obeyed it.”
“The history of the Church subsequent to the apostolic age demonstrates that succession is no guarantee against heresy. Bishops from all the major sees of Christendom, including that of Rome and those of innumerable lesser sees, have, at one time or another, been infected with heresy. The Church fathers cautioned believers repeatedly that bishops were to be followed only if their teachings conformed to Scripture and rejected if they did not. No Church father believed the Church as a whole to be infallible. The opinion was that individual bishops, as well as bishops in Council, could err. It is our contention that the early Church fathers, with unanimous voice, point us back to holy Scripture as the only infallible norm. The Church is not infallible. The Scriptures alone, being God—breathed and therefore inspired, are the only infallible norm for the Church.” [Source: David T. King, Holy Scripture: The Ground And Pillar of Our Faith, Volume 1 (WA: Christian Resources Inc., 2001), 138-139].