Clean and Unclean: Impurity of Places

In the Old Testament we find the idea that certain places are holy because of the presence of the Lord. No impurity could enter such places. Sacred places could become impure in any of the following ways:

The holy land of Israel could be defiled by oppression (Ezekiel 22:24) or by forbidden religious practices (Joshua 22:17; Ezekiel 36:17).
The holy city of Jerusalem could become impure through sin (Lamentations 1:8), idolatry (Jeremiah 13:27), the blood of murder (Lamentations 4:15) and by the ruins of the Temple (Haggai 2:10-19).
The Temple became impure if unclean persons or objects entered it (Nehemiah 13:9). The sanctuary was also defiled by the sins of the people. On the Day of Atonement each year the defilement was removed through a ritual (Leviticus 16).