Deuteronomy 12-26 forms the heart of the book and probably was the "book" (scroll) found in the temple that inaugurated Josiah's religious reforms (2 Kings 22-23). The law code begins with the cardinal Deuteronomic principle of the centralization of worship in Jerusalem. Six times in this chapter it is affirmed that Israel may only sacrifice in "the place that the LORD your God will choose" (vv. 5, 11, 14, 18, 21, 26). Exodus 20:24 had set forth the principle: "You need make for me only an altar of earth and sacrifice on it your burnt offerings and your offerings of well-being, your sheep and your oxen; in every place where I cause my name to be remembered I will come to you and bless you." In other words, those places where God had been revealed became places of sacrifice; there was no one, centralized place for worship. Down through the generations, worship places were situated on hills or other high places, often in forests, sometimes in groves of trees. Many of these sites were former Canaanite places of worship. This, of course, became the problem. The priests responsible for Deuteronomy were wary of Israelite use of Canaanite high places for worship. The risk that elements of Baalism would corrupt their understanding of the faith was too great. This would especially be true if Deuteronomy began as a northern tradition, since the northern kingdom was plagued with numerous places of worship; every city had its own shrine, and, as we learn from the condemnations of the prophets (for example, Hosea 8:11-14), they were as likely to be sacrificing to Baal as to the Lord. Such activity ultimately led to the destruction of the northern kingdom (2 Kings 17:7-18).
Deuteronomy 12 seeks to defend the purity of Israelite religion by reducing or eliminating the contamination of Baalism. This is accomplished by forbidding them to take over former Canaanite shrines, indeed, to "demolish [them] completely," and by allowing sacrifice only "in the place that the LORD your God will choose." This phrase is an oblique way of referring to "Jerusalem," which could not explicitly be named before the time of David. To name it now would confuse the literary setting of Deuteronomy as a farewell address of Moses to the people prior to their entry into the promised land. This limitation of worship and sacrifice to Jerusalem affected every aspect of Israel's individual and corporate life. It is the most important legislation in Deuteronomy.
12These are the statutes and ordinances that you must diligently observe in the land that the Lord, the God of your ancestors, has given you to occupy all the days that you live on the earth.
2 You must demolish completely all the places where the nations whom you are about to dispossess served their gods, on the mountain heights, on the hills, and under every leafy tree. 3Break down their altars, smash their pillars, burn their sacred poles* with fire, and hew down the idols of their gods, and thus blot out their name from their places. 4You shall not worship the Lord your God in such ways. 5But you shall seek the place that the Lord your God will choose out of all your tribes as his habitation to put his name there. You shall go there, 6bringing there your burnt-offerings and your sacrifices, your tithes and your donations, your votive gifts, your freewill-offerings, and the firstlings of your herds and flocks. 7And you shall eat there in the presence of the Lord your God, you and your households together, rejoicing in all the undertakings in which the Lord your God has blessed you.
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org