Anyone seeking for truth and wanting to go back to apostolic and biblical christianity rather than the mess that denominations and churches are in today, should read and study some early church writings to see how they believed:
http://www.achurchinfortcollins.org/eseh2.php#firstandsecond
Here's a good one:
Irenaeus, bishop of Lyons in France, c. 175
Irenaeus is widely valued as a vital link to the earliest days of the Church since he was taught by Polycarp, who was also taught by the Apostle John. This renders Irenaeus an expert on the question of eternal security. He also testifies that the Church had great unanimity in doctrine, even saying that he could go to an apostolic Church if a difficult question should arise.
Suppose there arise a dispute relative to some important question among us, should we not have recourse to the most ancient Churches with which the apostles held constant intercourse, and learn from them what is certain and clear in regard to the present question? For how should it be if the apostles themselves had not left us writings? Would it not be necessary, [in that case,] to follow the course of the tradition which they handed down to those to whom they did commit the Churches? (1:417)
For, although the languages of the world are dissimilar, yet the import of the tradition is one and the same. For the Churches which have been planted in Germany do not believe or hand down anything different, nor do those in Spain, nor those in Gaul, nor those in the East, nor those in Egypt, nor those in Libya, nor those which have been established in the central regions of the world. (1:331)
In theory, Irenaeus is extremely likely to support eternal security -- two links removed from John, he writes about unanimously held, pure, apostolic beliefs in the Church, and he has visited apostolic Churches personally. The Calvinist is very excited to see what Irenaeus believes about eternal security. But after referring to a certain presbyter older than himself, Irenaeus writes:
We ought not, therefore, as that presbyter remarks, to be puffed up, nor be severe upon those of old time, but ought ourselves to fear, lest perchance, after [we have come to] the knowledge of Christ, if we do things displeasing to God, we obtain no further forgiveness of sins, but be shut out from His kingdom. And therefore it was that Paul said, "For if [God] spared not the natural branches, [take heed] lest He also spare not thee, (1:499)
This statement of Irenaeus, combined with what we showed previously, is tantamount to saying that conditional security has always been the view held by the Churches, and therefore the same doctrine handed down by the apostles. The same can be seen in this single quotation, which we have abbreviated below. He directly states that the Church has always taught conditional security:
The Church, though dispersed through our the whole world, even to the ends of the earth, has received from the apostles and their disciples this faith: [She believes] in one God, ... and in one Christ Jesus, ... and in the Holy Spirit ...[and He will] confer immortality on the righteous, and holy, and those who have kept His commandments, and have persevered in His love, (1:330-331)
More quotations could be produced to show Irenaeus' belief in a conditional security (see also 1:500, 522, 525), but the previous two are sufficient. Again, this is not merely Irenaeus' personal view. Rather, it is the universal, pure, apostolic doctrine of the Church, and of his mentor Polycarp, and of Polycarp's mentor the Apostle John. In fact, the testimony of Irenaeus alone should be sufficient to cause our Calvinist friends to abandon their doctrine. Yet we will continue to search for eternal security among even earlier fossils.