Early Church Fathers Didn’t Do Any Verification
A common claim is that the early Church Fathers verified the historical claims of their faith. That’s why there is no substantial written evidence for what the Gospels and other books of the Bible. This is unfounded and the reality is they didn’t verify anything.They didn’t historically investigate the claims of the Gospels or Paul. They literally just read the Gospels and believed them to be true without investigation.
Why Did The Church Fathers Believe?
The early Christian church did not verify what their holy texts claimed. The four elite scholars in the Early Church were Justin, Athenagoras, Aristides, and Tatian. Quadratus would be included but we don’t have any extant writings to determine if he fact checked anything.
Justin Martyr had a “The scriptures say so, therefore it is true” type of attitude. He never mentions checking the claims of his faith against any kind of independent source. He had no interest in verifying the authors of the Gospels. He never talks to anyone even claiming to even be a descendent of an eyewitness. Justin does cite the Acts of Pilate as a reliable authority even though it’s a forgery which casts into doubt his ability to verify historical claims.
this should now be obvious to you-that whatever we assert in fonformity with what has been taught us by Christ, and by the prophets who preceded Him, are alone true, and are older than all the writers who have existed
Justin fundamentally believed that everything in the Gospels were true just by being in the Gospels. Just ended up believing the Gospels were true because they were “based on the oldest and thus most venerable of prophetic books.” 
Same goes for the other early church scholars.
The Gospel accounts were written anonymously 40 years after the events they supposedly record. Even then only one Gospel could be considered somewhat independent and that’s Mark. Mark doesn’t even cite historical sources. He cites scriptures and that’s all. Look at how he starts out his gospel:
The beginning of the good news about Jesus the Messiah, the Son of God, as it is written in Isaiah the prophet:
“I will send my messenger ahead of you, who will prepare your way”—
“a voice of one calling in the wilderness,
‘Prepare the way for the Lord,
make straight paths for him.’”
This continues and even becomes more aggregious in later Gospels.
All this took place to fulfill what the Lord had said through the prophet: “The virgin will conceive and give birth to a son, and they will call him Immanuel” (which means “God with us”).
So, nothing in the Gospels are sourced to any real person. They only have their supposed “prophecies” from the Septuagiant. How can you claim that these documents are reliable when they only source they have is prophecies?
Another issue is that none of these Gospels name their authors. The names of the gospels come from Church fathers in the 2nd century. Most notably, early church father Papias is cited as first reporting the authors. But, Papias is so unreliable that there is no reason to even consider this to be historically accurate.
Mark is only somewhat independent because he most likely used Paul’s theology to generate his own gospel. Matthew was written after Mark because he copies Mark directly. Most of Mark is in Matthew. Matthew was probably writing in the 80s. Luke-Acts didn’t come till the end of the first century so none of its “history” is actually history. He borrowed from people like Josephus to give his account some historical look and feel but the things it claims cannot be true due to the timeframe in which it was written.
The church was never documenting history. They documented theology.