The main importance of Genesis 12:1-3 are the three promises given that have become known as 1.) the Land Promise, 2.) the National Promise, and 3.) the Spiritual Promise:

1. "...a land that I will show you." (v1)
2. "...a great nation." (v2)
3. "...all peoples on earth will be blessed through you." (v3)

As a result of these very promises, Abram was used as the leader in and for the Jewish nation to express God's heart throughout the world.  Because Abram listened and obeyed, though there were hardships, ultimately, throughout the remainder of the Old Testament, Israel remained God's "chosen people."  This meant they were saved and protected always, and continue to survive today, even through great turmoil and conflict.

These verses are the foundational moment for what would eventually be fulfilled in the New Testament with the coming of the messiah, Jesus Christ, who was a descendant of Abram.

The passage defines the very origin of the Jewish nation as well as the land of Palestine.  Many believe these promises are also at the heart of the current conflict between Israel and Palestine.