Whilst I also agree with your premise that the early church fully understood the gift of salvation through Jesus Christ and that it had the completed Bible which was able to make individuals wise unto salvation, that the Holy Spirit was able to convict and convince men of the only way to the Father, via Jesus Christ. I must however disagree that the early church was without the same pernicious errors we see today, essentially the exact same errors concerning the deity of Christ, His bodily resurrection, the mixing of law and grace, salvation of grace but going on by works, the eternal security of the believer, the rise of a one man clergy / laity system, that some said Christ had already returned and many more besides. This is the reason why many of the epistles were written, to refute both the error and the men who promoted such error.
Paul was constantly hounded by the dogs of the circumcision, Christ was constantly being degenerated at every opportunity by teachers of mans wisdom, professing themselves wise, they became fools. There have been Gnostics who say that they have a special revelation from God, knowledge that other Christians do not have, that only by adhering to their group will the clear intent of Scripture be revealed. There are those who go from house to house, who are ever learning yet never able to come to a knowledge of truth.
These are sill with us today in their various guises. The way of salvation has not changed. It is by FAITH not works.
Rom 1:17 For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith. The GOSPEL has not changed. 1Cr 15:1 Moreover, brethren, I declare unto you the gospel which I (Paul) preached unto you, which also ye have received, and wherein ye stand 1Cr 15:2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain.
1Cr 15:3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures 1Cr 15:4 And that he was buried, and that he rose again the third day according to the scriptures: The PENALTY for preaching another gospel has not changed. Gal 1:8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, LET HIM BE ACCURSED.. Gal 1:9 As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, LET HIM BE ACCURSED.. That the gospel is the way of reconciliation to God through Jesus and neither anyone or nothing else is clear; it is the NAME OF JESUS Act 4:12 Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved. An example of salvation is recorded in Scripture, it did not require hours and hours of teaching, nor hours and hours of witnessing.
The ANSWER to the jailers question was simple and COMPLETE.
While I agree with your premise, this affects other denominations that claim to be Christian, also. Some might argue that we cannot gain salvation without obeying a whole list of doctrines that are based on eisegetical concepts.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.