Answer 1
Because all three religions have spiritual connections to it.
Answer 2
If you meant the question as phrased, it is based on an incorrect belief. The three most dominant Eastern Faiths are Hinduism, Buddhism, and Daoism and none of those (as well as Shintoism, Animism, and Ancestor Worship) have any connection to Jerusalem and have never made assertions to that effect. If you meant to say the 'three Western Religions' then, yes, Judaism, Christianity, and Islam all have connections to Jerusalem. See the link below for a detailed description.
Jerusalem is considered holy by all three religions.
Jerusalem, the holy city
The holy city claimed by all three major monotheistic religions (Christianity, Judaism, and Islam) is Jerusalem. It is a city of significant religious importance and holds key sites such as the Western Wall, the Church of the Holy Sepulchre, and the Dome of the Rock.
Jerusalem is a holy city for the Abrahamic religions: Judaism, Christianity, and Islam. To other faiths it is not a holy place.
Jerusalem is the holy city that all 3 religions claim.
Christians, Jews and Muslims, in no particular order. These being the people of the book. Also it is respected by any faith which respects those above religions such as Bahai and devotees of the recently deceased Sai Baba, who embraced all religions. Hindus, Bhuddists, Animists and all the other major religions have no special regard for Jerusalem.
The Middle East, in particular the city of Jerusalem in Israel has holy sites for all 3 of those religions.
Jerusalem. This is the same place Jews and Muslims go as all 3 religions see this city as their "Holy City"
The Middle East, in particular the city of Jerusalem in Israel has holy sites for all 3 of those religions.
Jerusalem
Yes. The three monotheistic religions (of which Arabs and Israelis are mainly composed) all venerate the city.
All three monotheistic religions (Judaism, Christianity, and Islam) have important holy sites in Jerusalem.