SEARCH FOR JERUSALEM
The Torah portion opens with the instruction to pronounce the blessings and curses on Mount Gerizim and Mount Eival. The Torah gives the location of these two mountains very precisely: "They are across the Jordan, just beyond the Sunset highway, on the way to Gilgal, near the Plains of Moreh, in the territory of the Canaanites who lived in the flood plain" (Deuteronomy 11; 30). This is in sharp contrast to another mountain mentioned in the portion, to which the Torah gives us no geographical clues: "There will be a site that G-d will chose as the place dedicated to His name" (ibid. 12; 11). This is referring to Mount Moriah, the Temple Mount in Jerusalem, yet we find no explicit mention of Jerusalem anywhere in the five books of Moses. Several times it says "In the place that He will chose to dwell" (e.g. ibid. 16; 16). Since at the end of our Torah portion we find the commandment to appear before G-d at the place that He shall chose, why does He not tell us exactly where that place will be?
There are many answers given to this question (e.g. Tzena u'Rena on this week's portion) but the answer of the Birkas Mordechai seemed most appropriate.
The Talmud (Zevachim 54b) describes the great lengths to which King David and Shmuel went to in order to discover the exact place where the Temple was to be built. Only through days and nights without sleep were they able to finally arrive at the correct location.
We find elsewhere in the Torah that the site of the Temple Mount is only described in vague terms. When Avraham is told to go and offer Yitzchak as a sacrifice, G-d tells him "Go to the land of Moriah, and offer him there for a burnt offering on one of the mountains which I will tell you." (Genesis 22; 2). Rashi there explains that "G-d delays with the righteous, and only reveals to them their task later, in order that they should receive more reward." This seems strange, why should G-d withhold information from the righteous? And why would the lack of knowledge increase their reward?
Similarly with Ya'akov, the Torah says "He encountered that place, and slept there..." (ibid. 28; 11). Rashi (ad loc.) explains that 'that place' refers again to Mount Moriah, the 'place' mentioned earlier in the text (in connection to Avraham).
The Birkas Mordechai explains that the search for the location of the Temple is part of the Mitzvah of building the Temple. The location of the mountains upon which the blessings and curses are to be given is made explicit in the text, just as the blessings and curses are accessible to everyone through their actions. Blessings or curses are the automatic results of any deed, either positive, or the opposite. However the Temple, which symbolises the point of interaction between mankind and G-d, is not easily accessible. Before we can find the location of the Temple we must search for G-d in the world. When we find G-d, and recognise His interaction with the world, then we can begin to find the exact focus of that interaction. Only through the struggle of locating the Temple is it possible to fulfil the Mitzvah of building the Temple. This is actually implicit in the verse: "There you shall search for Him at His dwelling" (Deut. 12; 5).
This explains why G-d did not immediately reveal to Avraham the location where he was to offer his son. Through giving him the opportunity to search out the site himself, G-d allowed Avraham to take a greater share of the reward for the Mitzvah of listening to what he had been commanded.
Perhaps with this we can also explain the wording of the Halacha. The Shulchan Aruch (based on the Talmud Brachot 30a) states that "When a person stands up to pray, they should face the direction of Jerusalem, and the site of the Temple" (Orach Chaim 94; 1). However, "One who is unable to discern the correct direction should direct their heart to their Father Who is in Heaven." (ibid. 3). Why does the Shulchan Aruch not state that a person should at least direct their heart to Jerusalem? We can explain allegorically that unless they first direct their heart towards G-d, and commit themselves to searching for the Divine in this world, they will not be able to discern the site of the Temple.
Perhaps this is also the reason that the Temple is known as Beis HaBechira, 'the house of free choice'. It is the place which can only be discovered by one who has used their free choice to search out G-d in this world.