The first covenant between God and Abraham was repeated 5 times: He said that He will bless Abraham and his decendants, so that they (His people) can bless others (the unsaved).
This is profound. Let me explain.
God chose the Israelites to make them a great nation and to cause the unbelieving nations to become jealous so they will want to have God for themselves.
In several places God blessed the unbelieving nations around Israel. He spoke about letting unbelieves who followed Him become Israelites. He spoke in the psalms about placing the names of non-Israelites into the register of Israelite births.
Israel was to be blessed, in order to bless the nations around them. But the israelites began to treat themselves as the only chosen nation and began to shun the unbelievers. (The people dressed in black at the wailing wall still feel this way!)
This was not what God had in mind.