As far as the pronunciation of ancient Greek is concerned, there's the dominant thesis that the pronunciation invented by the widely reknown Dutch philosopher, Erasmus of Rotterdam, is the correct way of delivering ancient Greek phonology.

That could not be further from the truth.

In fact, the Erasmian pronunciaton is nothing but an aide in helping speakers of Dutch and all the Germanic languages to better comprehend ancient Greek.

As we all know, the most direct descendant of classic Attic Greek is Koine Greek, which came to the surface in the Hellenistic Age, has the same pronunciation as modern Greek. So, truthfully speaking, how could the invented pronunciation of a Germanic philosopher be closer to the original pronunciation of ancient Greek than its natural successor, Koine Greek? The answer is that it's not. The Erasmian pronunciation is only a guide aided to helpspeakers of the Germanic languages to better understand ancient Greek. How is that proved? By simply looking how the Erasmian method treats dipthongs and labial and dental consonants.

There is no dipthong in Koine Greek that has basically its two letters pronounced differently, as in Germanic languages. For example, in Erasmus' mother tongue, Dutch, there's the word "ijselmeer". The dipthong here is IJ. It's like ay. The vowels in ay are pronounced differently than one another. That doesn't happen in Koine Greek, the direct ancestor of Attic Greek. The dipthongs here are pronounced like one letter almost.

Then, as far as labial and dental consonants, we don't have hard sounding labial and dental consonants. We don't pronounce δέλτα as d in English, nor βήτα as b.

The only logical explanation for the above is that Erasmus created this pronunciation in order to aid his countrymen to better translate ancient Greek, in order to suit their phonology. And as the most related language to Dutch, English, overruled, so did the Erasmian pronunciation gain momentum, as both are Germanic languages, and as a Germanic language dominated, the need to translate ancient Greek according to the phonology of these Germanic languages.