Gutenberg was catholic and printed catholic texts. There is no indication he supported heretics like Martin Luther who used Gutenberg’s invention to print texts the Catholic church viewed as heretical. There were many many heretics before Marin Luther but the critical reason why Luther succeeded was he has the ability to spread his teachings much farther.

https://blogs.loc.gov/international-collections/2023/10/man-behind-the-bible-johannes-gutenbergs-life-of-adventure-and-art-loclr-blogint/#:~:text=Gutenberg%20had%20realized%20his%20goal,Latina%2C%20Mainz%201454–55.