The materials were written by "just people writing from the heart". Their inclusion in the canon was by a screening process ultimately controlled by church leadership.
Politicians and church leaders benefit from keeping the game going. Politicians like to control the masses, and church leaders enjoy the power and the easy money.
If you want me to pin it down to one person, I would say Paul. http://www.hipforums.com/newforums/showthread.php?p=5357160#post5357160
The letters of the Epistles helped to further explain the Christian faith to the young church. It can be viewed as either a controlling of the masses or as a further clearing up of what it means to be Christian as described throughout the Bible. We can either believe that Paul experienced what he experienced which lead him away from persecuting the Christians, or that he made it all up. It's really up to everyone to decide that on their own. I just believe what he said to be true because it seems to follow along with what the rest of the Bible has said and seems helps to settle deeper questions of faith. So while Jesus outlined the principals, the letters further expands on those principals and how to apply it in our day to day lives.
Paul saw and opportunity, and he jumped on it. It's up to us to decide whether that was a good thing or a bad thing. I think he was the first guy to figure out that he could become a locally famous leader and get lifetime financial support without working. Untold thousands of manipulative preachers have followed his example. Jesus spent years training his disciples - which did not include Paul - and they, led by Peter, taught a gospel that was quite incompatible with Paul's. They taught continued observance of Jewish law, along with spiritual reform. Their approach much more closely follows what the rest of the Bible has said. Their sect did not survive. Paul's branch survived because it was useful to the Roman government.
Although Paul was well educated, he worked as a tent maker to support himself and his ministry in order to NOT be a burden on the congregations. (Acts 18:2-3; 2 Corinthians 11:7; 1 Thessalonians 2:9; 2 Thessalonians 3:7-8) Luke, who wrote the book of Acts, wrote about the observance of Jewish law regarding circumcision at Acts 15:1-33 and it points out that Paul did not unilaterally decide to speak out against observance of Jewish law but that he and Bar′na·bas went to the apostles and older men in Jerusalem regarding this dispute and the apostles and the older men gathered together to see about this affair. At that time , Peter rose and said to them: “Men, brothers, YOU well know that from early days God made the choice among YOU that through my mouth people of the nations should hear the word of the good news and believe; and God, who knows the heart, bore witness by giving them the holy spirit, just as he did to us also. And he made no distinction at all between us and them, but purified their hearts by faith. Now, therefore, why are YOU making a test of God by imposing upon the neck of the disciples a yoke that neither our forefathers nor we were capable of bearing? On the contrary, we trust to get saved through the undeserved kindness of the Lord Jesus in the same way as those people also.” James also spoke, saying: “Men, brothers, hear me. Sym′e·on (Peter) has related thoroughly how God for the first time turned his attention to the nations to take out of them a people for his name. And with this the words of the Prophets agree, …. Hence my decision is not to trouble those from the nations who are turning to God, but to write them to abstain from things polluted by idols and from fornication and from what is strangled and from blood.” Then the apostles and the older men together with the whole congregation favored sending chosen men from among them to Antioch along with Paul and Bar′na·bas, namely, Judas who was called Bar′sab·bas and Silas, leading men among the brothers; and by their hand they wrote: “The apostles and the older men, brothers, to those brothers in Antioch and Syria and Ci·li′cia who are from the nations: Greetings! Since we have heard that some from among us have caused YOU trouble with speeches, trying to subvert YOUR souls, although we did not give them any instructions, we have come to a unanimous accord and have favored choosing men to send to YOU together with our loved ones, Bar′na·bas and Paul, men that have delivered up their souls for the name of our Lord Jesus Christ. We are therefore dispatching Judas and Silas, that they also may report the same things by word. For the holy spirit and we ourselves have favored adding no further burden to YOU, except these necessary things, to keep abstaining from things sacrificed to idols and from blood and from things strangled and from fornication. If YOU carefully keep yourselves from these things, YOU will prosper. Good health to YOU!” Accordingly, when these men were let go, they went down to Antioch, and they gathered the multitude together and handed them the letter. After reading it, they rejoiced over the encouragement. So it would seem that Paul did not go out on his own in this matter but was in agreement with Peter, James and the apostles and older men in Jerusalem.
You can get people to do just about anything if you know how to provoke fear inside of them. Organized religion is just verbal manipulation at a whole new degree.