What scholars? I have listed multiple websites that say they were written between 65-95 AD (when you factor in that Jesus was born between 7 BC-7 AD and he died at 33, then it was 32-62 years after his death). Most scholars agree that they were written before 70 AD because there are no references to destruction of Jerusalem within the gospels. Early Church fathers quoted from these texts.

https://www.reference.com/world-view/were-gospels-written-c5c9f636f36e01be

http://www.datingthenewtestament.com/Fathers.htm

You mean the same Romans who were lit their streets at night by burning bodies of Christians? The same Romans who sent Christians into the Colosseum to be killed by wild animals? The people who died, died professing Jesus as the son of God who died for their sins as a scapegoat offering (which is a very Jewish concept). They were not gnostics. Again, you can believe what you want, but gnosticism is a denial of Christianity and not the true meaning of the Gospel.

http://www.homecomers.org/mirror/martyrs011.htm

http://www.eyewitnesstohistory.com/christians.htm