"Why did God choose Israel to be His chosen people?"
Answer: Speaking of the nation of Israel, Deuteronomy 7:7-9 tells us, “The LORD did not set His affection on you and choose you because you were more numerous than other peoples, for you were the fewest of all peoples. But it was because the LORD loved you and kept the oath He swore to your forefathers that He brought you out with a mighty hand and redeemed you from the land of slavery, from the power of Pharaoh king of Egypt. Know therefore that the LORD your God is God; He is the faithful God, keeping His covenant of love to a thousand generations of those who love Him and keep His commands.”
God chose the nation of Israel to be the people through whom Jesus Christ would be born—the Savior from sin and death (John 3:16). God first promised the Messiah after Adam and Eve’s fall into sin (Genesis chapter 3). God later confirmed that the Messiah would come from the line of Abraham, Isaac, and Jacob (Genesis 12:1-3). Jesus Christ is the ultimate reason why God chose Israel to be His special people. God did not need to have a chosen people, but He decided to do it that way. Jesus had to come from some nation of people, and God chose Israel.
However, God’s reason for choosing the nation of Israel was not solely for the purpose of producing the Messiah. God’s desire for Israel was that they would go and teach others about Him. Israel was to be a nation of priests, prophets, and missionaries to the world. God’s intent was for Israel to be a distinct people, a nation who pointed others towards God and His promised provision of a Redeemer, Messiah, and Savior. For the most part, Israel failed in this task. However, God’s ultimate purpose for Israel—that of bringing the Messiah into the world—was fulfilled perfectly in the Person of Jesus Christ. http://www.gotquestions.org/why-God-choose-Israel.html