Commander wrote:In short, which book is considered as holy or sacred by the Buddhists, if there is any at all?
We'll want to plant a flag on the terms "holy" and "sacred" so we will be sure not to make mistaken assumptions on their account, but they'll do for now.
The best text to study, in a comparative sense when also reading the Quran, Tanakh ("old testament"), Gospels, Analacts, and so forth, is probably the Majjhima Nikaya. It covers the material with a balanced combination of doctrine and narrative context, which is why it compares well with the format of these other holy books.
You can read more about the Pali Canon
here, for a decent overview of core Theravada Buddhist texts. Alongside the Nikayas which comprise the Sutta section (the Majjhima Nikaya is one of these five), you will notice a Vinaya section (monastic rules & history) and an Abhidhamma section (extrapolation & commentary). These texts function similarly to the way the Talmud or the Hadiths or the Catechism of the Catholic Church are used, in case you are familiar with any of those.