The authorship of the gospels and their undeniable veracity

The rejection of Christianity requires the rejection of the veracity of the gospels, and of course of the entire Bible in general, but the gospels contain the direct contemporary accounts of Jesus' life on Earth. Because of this, atheists, jews, muslims etc. have come up with increasingly funny excuses to pretend they are some kind of unreliable fiction.

Those of lesser intelligence first claim that the events were some kind of dreamed fantasy by the authors, as if the hundreds of people involved in the years during Jesus' ministry and afterwards were all continously drunk and somehow partaking in a shared massive, continuous hallucination. This nonsense is old as time, with Origen already responding to Celsus' (a pagan hostile to Christianity) articulation of it regarding the appearances of Jesus after His crucifixion in Against Celsus, book 3, chapter 60. Celsus writes:

That some one having so dreamed owing to a peculiar state of mind, or having, under the influence of a perverted imagination, formed such an appearance as he himself desired, reported that such had been seen; and this has been the case with numberless individuals.

And Origen answers the obvious:

But Celsus, unwilling to admit any such view, will have it that some dreamed a waking dream, and, under the influence of a perverted imagination, formed to themselves such an image as they desired. Now it is not irrational to believe that a dream may take place while one is asleep; but to suppose a waking vision in the case of those who are not altogether out of their senses, and under the influence of delirium or hypochondria, is incredible

The anti-Christ will then claim that the events are a lie made up by the writers of the gospels, which is refuted by just pointing out how the only thing they gained from their proclamations was a life of enduring constant suffering and a painful death when refusing to back down.

The core issue

This leads us to the core issue, to the final excuse that anti-christians are forced to use: the gospels are pretty much late fiction, written many years after the actual facts, and are only vaguely based on reality and the actual Jesus. For this to be the case, the gospels have to be late fabrications written by unknown authors rather than the contemporary evangelists and followers. In this theory, after Jesus' life, a large number of gospels with different stories circulated around with the four well-known ones simply being the ones that gained popularity and were imposed over the others. And of course, the apocryphal gospels are the proof of this: alternative gospels that were discarded because some evil man such as Athanasius made sure of it.

The late dating of the gospels is also a necessity for different reasons: the gospels contain the prophecy made by Jesus about the destruction of the temple (Mark 13). If the gospels were written before its destruction in 70AD, it would mean that there is a true prophecy in the gospels.

Let us now dissect this theory and check whether it holds up. According to it, there must be no support for the traditional authorship of the gospels.

What historical witnesses say about the authorship of the four gospels

To know who wrote a piece of text, the most natural intuitive way is to check what the earliest witnesses say about who wrote them. If the gospels are late fiction to which authors were attributed with time to give them credibility, one would expect that in different places and times there would exist different, contradictory traditions about who wrote them. The early attributions of the authorship are the following ones:

Tertulian (~200AD) in North Africa, in "Against Marcion", book 4, chapter 2, states that the authors of the gospels are John, Matthew, Luke, and Mark.
Saint Irenaeus of Lyon (~180AD) in Alexandria, in "Against heresies", book 3, chapter 1, states that first Matthew wrote a gospel in his own dialect (hebrew/aramaic), also Mark, as Peter's disciple and interpreter, wrote his. Also Luke, Paul's companion. Then later after these, John.
Eusebius (~290AD), Church historian, cites Clement of Alexandria (~180AD) in the fragments of his works as having transmitted a tradition from the elders before him according to which the gospels with genealogies (which would be Matthew and Luke though the names are not mentioned) were written first, then Mark, and finally John.
The remaining parts of the Muratonian fragment (~170AD), having a missing beginning, mentions how the third gospel was Luke, and the fourth one John.
Eusebius of Caesarea (~270AD), in his "History of the Church", book 3, chapter 39, cites Papias of Hierapolis (~125AD) as describing how Mark wrote his gospel after Peter's preaching and Matthew writing his discourse first in hebrew/aramaic.

As it can be seen, there is not a single ancient tradition that mentions different authors. All early attributions are consistent and mention the same authors so the matter should be settled. There are no mentions of other gospels or other authors.

An interesting detail is how it is mentioned that Matthew first wrote his gospel in hebrew/aramaic. Probably because a first version was written in his native language, with the greek version that we have being written afterwards by Matthew as a "proper" gospel. This first version by Matthew would precisely be the ancient source for material shared by Matthew's greek gospel and Luke's that some people have called "Q": Matthew merely reused his own material, and Luke would use it as part of his compillation of information. There is therefore no Q, only the early version of Matthew.

Also, the gospels of Luke and Mark are attributed to relatively unremarkable figures: companions of apostles. Forged gospels usually present themselves as having been written by important figures in order to have more weight, such as the gospel of Thomas, the gospel of Peter, etc.

What historical witnesses say about the number of gospels

As it was mentioned earlier, denying the authorship of the gospels requires affirming that they are just four pieces of late fiction among many that just happened to gain popularity. Therefore, if this theory is true, the earlies cites of Scripture should equally cite those other gospels and refer to arbitrary numbers of existing gospels.

However, the earliest Christian writings (e.g. the Didache, from the first century, or Church Fathers like Ignatius of Antioch) only quote the four well known gospels, and not, for the example, the apocryphal ones (the gospels of Thomas, of Truth, of Peter, etc) nor other ones. These only start to be mentioned at the late second century, and frequently to declare them to be heretical and false. Even attacks by early pagans such as Celsus only quote the four gospels.

For example, Tatian, disciple of Justin Martyr (~120-180AD) wrote a harmonization of the gospels called "Diatessaron". The name literally means "made of four" and compiles the contents of the four known gospels, again showing that since the earliest times there were four gospels, not many, or others.

Is the content of the gospels consistent with their early dating?

Yes, the internal evidence is consistent with what we would expect from early writings. Specifically, the first three gospels (Matthew, Mark, Luke) would have been written before 70AD, with John being written later as accounted by all the existing traditions. Here are some of these reasons:

None of the gospels mention directly the destruction of the temple, which was predicted by Christ. However the gospels frequently mention how prophecies have come to pass as if they indeed have already, such as the betrayal of Judas or Acts 11:28.
There is no animosity towards Romans nor any sign of the persecution Nero caused around 65AD, neither in the gospels nor in Acts.
Matthew focuses on a hebrew audience, but such audience was dispersed and destroyed by the jewish wars and the destruction of the temple. Therefore it is more likely that it was written before them.
Some names of important witnesses are omitted in the first three gospels but mentioned in John's, such as the identity of the Apostle who cut off the ear of a Roman soldier (Peter), or people who helped Jesus. This may be because the first three gospels were written before the loss of jewish power and influence, while John's was written afterwards.
The Book of Acts finishes just after Paul's arrest and arrival to Rome, without mentioning the outcome of his trial. Paul was acquitted, which would have been a nice ending to the book, but this is not mentioned probably because it was written just before. Because of the aforementioned government transitions, the arrival to Rome would have taken place at around 60AD. Acts presents itself as Luke's second book. Therefore, his gospel would have been written before 60AD.
The gospels and the Book of Acts mention endless perfectly accurate historical details related to governors, taxes and coins, etc. This is itself a full-fledged topic on which many volumes have been written, including authors who traveled to Jerusalem hoping to find evidence that would discredit the gospels, and found exactly the contrary.
There are many instances of gospels passingly mentioning details that perfectly match when compared to the other gospels, showing their incredible consistency. For example, John 6 mentions that Jesus asks Philip where to buy bread without explaining why the question was made to Philip. Luke mentions that the miracle of the multiplication of the bread and fish took place in Bethsaida, but doesn't mention Philip. And John 12 mentions that Philip was from Bethsaida. Lydia McGrew compiles these in "Undesigned Coincidences in the Gospels and Acts (2017)".

What about the objection to the authenticity of the gospels?

Since as can be seen all evidence strongly supports the traditional authorship and authenticity of the gospels, one would imagine that those that deny them must have great objections. Let us take a look at some of them:

Matthew couldn't have written Matthew because he would be talking about himself in the third person

Some people like Bart Erhman have actually used this as an argument, which Augustine already dismisses as complete foolishness in "Against Faustus", book XVII (written around the year 400AD). As Augustine says, everyone knows historians usually describe events involving themselves in the third person.

The gospels are not consistent. For example, John identifies Jesus as God while Matthew doesn't

These objections are always based on bad theology. For example, all gospels identify Jesus as God.

Mark 7:3 describes how all jews washed their hands before eating according to their traditions, but this is false since only priests followed these rites. Therefore, the author couldn't be a contemporary hebrew since he didn't know these customs

It takes some serious blind pride to claim having better knowledge of ancient traditions 2000 years later than those who lived in that time period. While the instructions in Pentateuch refer to priests, it is not strange that ordinary people would do the same. John 2:6 describes the use of huge water jars for ceremonial cleaning. Other writtings also describe how the cleaning customs were practised by all jews (e.g. the letter of Aristeas, 305)

Mark 7:31 describes a route from Tyre to Bethsaida passing through Sidon. However, this route makes no sense, since Sidon is not between Tyre and Bethsaida, proving that the author did not know the geography of the zone.

There is high, irregular terrain between Tyre and Bethsaida making travel in a straight line impossible, thus requiring a detour:

Conclusions

All historical witnesses affirm the traditional authorship of the gospels. All early citations cite the content of those, and not other gospels. All references to the number of gospels say that there are four gospels and their content supports their authorship and authenticity Finally, the objections are poor attempts at wanting to be more knowledgeable about the times than people who actually lived then.

Therefore, the gospels were written by their traditional authors, who were witnesses and followers of Jesus. Therefore, their content is true, and the life and miracles of Jesus are undeniable.