Parshat לך לך introduces us to Avraham Avinu and how he found G-d and ultimately changed the world. The Talmud tells us that the first 2000 years after creation, were תהו ובהו, nothingness, the second 2000, Torah, and the third 2000, Mashiach.
Avraham was born 1948 years after creation which means that the 2000 years of Torah began when he was fifty two years old.
His search for truth was a long journey that required him to leave his home and family, and begin his new life in the Land of Canaan with his new mission of teaching monotheism to the world.
The Rambam said that he knew that Hashem existed at a young age but he was forty when he recognized the creator. Hashem first revealed Himself to Avraham when he was seventy five years old. He never gave up being a man of faith.
Rabbi Soloveitchik writes that his relationship with Hashem intensified over the years. By the time Avraham did Brit Milah, this relationship went from father to brother to friend. Very few in history were able to reach such a level of closeness to G-d.