"The Lord had said to Abram, 'Leave your country, your people and your father's household and go to the land I will show you. I will make you into a great nation...'." Genesis 12:1-2 (NIV)
Imagine Abram's thoughts when he first found out what God had promised him. He and his wife are old, and childless, yet here God is promising him not only an heir, but a nation, and a great one at that. He must have been thrilled, and puzzled. How would God bring this about? The seventy-five year old Abram set off for Canaan with his wife and nephew Lot and their possessions and servants. At Shechem, an important Canaanite city and the site of the great tree of Moreh, the Lord appears to Abram and tells him that He will give this land to Abram's offspring. (v.7) Abram builds an altar to the LORD, as if to acknowledge that he is continuing to trust and to serve the true God. He continues to travel until he comes to the place between Bethel (north of Jerusalem) and Ai, where he builds another altar. He builds several more of these altars as he travels (see Chapters 15, 18, 17, and 22), probably both to use for worship and also as if to say that this land belongs to God.
Flash forward to the present, where Israel is indeed a great nation, both in numbers and in its contributions to the world. More on this later. God always keeps His promises.