Sunday-The main day of worship :)
Christianity, as a whole, has only one 'Holy Book' and that is the Bible. There are various versions of it in translation around the world.
Judaism, Christianity, and Islam have all claimed the Holy Land for themselves.
Jerusalem, the holy city
Christianity is holy as god is holy and we are his children.
The three religions.
Believe in The Father, Son, and Holy Spirit.
The main site shared Holy by these three religions is Jeruselum.
There are more than three Jewish holy days, but the answer you're looking for is Rosh Hashanah and Yom Kippur, which total three days. For more about these and the rest of the Jewish holy days and other occasions, see this linked page.
Sunday, Easter, Christmas, Pentecost, & various Saints' Days.
the matter of opinion of the individaul christain as the bible says
.Roman Catholic AnswerThe three most Holy Days of the year are usually considered Easter, Pentecost, and Christmas.