Curiously, he was a christian priest of some kind (its not known which denomination he belonged to?), and he wrote a book called Risâle-i Islâmiyye where he quotes biblical verses in latin, transliterated to ottoman script, mentioning "Ahmedus" (Ahmad, the alternative name for the islamic prophet, with a latin suffix -us). I read the manuscript but did not have the skills to translate the ottoman-latin to something I could understand.
I uploaded the manuscript I found in Istanbul to Picasa, but unfortunately those files seem to have gone lost when they shut down.
https://the-public-domain-review.imgix.net/collections/the-m...
To a detail image I found elsewhere: https://i.imgur.com/Iiyfgrn.jpg
https://commons.m.wikimedia.org/wiki/Category:Matrak%C3%A7%C...