From what I can see the majority of the early Fathers taught salvation by works. Here are a few of many possible quotes. (I also noticed after typing this that Greg has started another thread with a load more quotes).
"Man was not created perfect, but created suitable for acquiring virtue... For God desires us to be saved by our own efforts." -(Clement of Alexandria, ~200AD, Stromata 6.12.96)
And we have been taught, and are convinced, and do believe, that He accepts those only who imitate the excellences which reside in Him, temperance, and justice, and philanthropy, and as many virtues as are peculiar to a God who is called by no proper name. And we have been taught that He in the beginning did of His goodness, for man's sake, create all things out of unformed matter; and if men by their works show themselves worthy of this His design, they are deemed worthy, and so we have receivedof reigning in company with Him, being delivered from corruption and suffering. For as in the beginning He created us when we were not, so do we consider that, in like manner, those who choose what is pleasing to Him are, on account of their choice, deemed worthy of incorruption and of fellowship with Him." (1 Apol 10)
"The spirit must earn immortality by works of righteousness." (Lactantius : Ante Nicene Fathers, Volume 7, pg.127)
"I do not know if these commandments can be kept by man, because they are exceeding hard." [The Angel became extremely angry] and said to me, "If you lay it down as certain that they can be kept, then you will easily keep them, and they will not be hard. But if you come to imagine that they cannot be kept by man, then you will not keep them. Now I say to you, If you do not keep them, but neglect them, you will not be saved, nor your children, nor your house, since you have already determined for yourself that these commandments cannot be kept by man." -(Shepherd of Hermas, ~150AD, Commandment 12.3-4)
Notice theres nothing about Christ's righteousness being imputed or even imparted or infused here its all stuff we have to work up. The Didache even hints on the need for perfection:
"But come together often, seeking the things which are befitting to your souls: for the whole time of your faith will not profit you, if you are not made perfect in the last time." (Did 16:2)
As for post baptismal sin, it seems that Gods mercy runs out when you become a Christian, and there are only a certain amount of times you can be forgiven.
the Lord has sworn by His glory, in regard to His elect, that if any one of them sin after a certain day which has been fixed, he shall not be saved. For the repentance of the righteous has limits. Filled up are the days of repentance to all the saints; but to the heathen, repentance will be possible even to the last day. (Hermas Vis. II.2.1-6)
Tertullian was even stricter (he even thought the Shepherd of Hermas was too soft on the matter) and clearly thought that there was no forgives for sins (or at least some sins) after baptism:
"With no less reason ought the unmarried also to be delayed until they either marry or are firmly established in continence: until then, temptation lies in wait for them, for virgins because they are ripe for it, and for widows because of their wandering about. All who understand what a burden baptism is will have more fear of obtaining it than of its postponement." (De Baptismo, XVIII)
I must stress again, I DO believe we should fear the Lord. It's the kind of fear that I'm questioning. I see little security or assurance in the writings of the early fathers (and if there is, it's always based on ones own near perfect conduct, not Christ's blood), just this fearful dread that we may not be good enough to make it in the end.
I find it interesting that in Psalm 130 (oh how often I pray through this psalm)it says in v4
"But with you there is forgiveness,
that you may be feared."
I right reverent fear of God therefore comes the other side of knowing his forgiveness, it would seem.
A personal note here: I actually do have a daily real sense of the fear of God (though whether it's the right kind I sometimes doubt) and I would say I know it far more than I know the love of God, alas.