Merhaba.

Please take a look at the second sentence from this picture:

On my own I can figure out that it is something like: Although he was not Christian he ... the Noble Quran. Only the missing middle part is a mystery to me. What does it mean: hattim etmek? Is it the same word "hat" which means "a line"? So what is it here - my line? That doesn´t make much sense...

It simply means  - To finish a complete reading of the Koran.

And it should be written as " hatmetmek "  --> hatim etmek  [ "i" drops when it is written as one word ]

Thank you! Btw, it seems the additional "t" letter disappears as well

It is written wrong. Correct is ´hatim etmek´ with one letter T.

You can check it from TDK website.

http://www.tdk.gov.tr/index.php?option=com_gts&view=gts

Hristiyan olduğu halde - although he was a Christian

Plus on " 3000 golü attı. "  the  letter "ü" is extra there. It should be without "ü".