God being a just God why is he doing so many special favors only to the Israelites out of the whole world?
The choice of Israel by God is not a question of justice or injustice but of love. God chose Israel because it was part of his plan to bless humanity. It all goes back to Abraham’s faith. God chose Abraham because of his faith. His promise was to Abraham and to his “seed.” This seed was his people Israel, and it was his Son Jesus. God said to Abraham that he would make him into a great nation, and that, eventually, all the peoples of the earth would be blessed through him. This promise, was given after Abraham, by faith, obeyed and left Ur (Genesis 12:1-5). God’s plan was to choose a man of faith (which turned out to be Abraham), and through him, to create a people (Israel). His plan was to give Abraham’s descendants the land of Canaan, as he promised Abraham. This was not the end of the plan. He gave the Law of Moses to Israel, he gave them kings and prophets, all to prepare for the ultimate blessing, which was to come as God in the flesh through a descendant of Abraham. Once Jesus came in the flesh and died for our sins, the plan of God was completed and “all nations are blessed” through Jesus, the son of Abraham (Matthew 1:1).
God’s choice of Israel was not because they were so amazing. Not at all! Deuteronomy 7:7-9 expresses this beautifully! God chose Israel, not because they were so great, but because of his love for them. That special love was on account of the faith of Abraham. Again, this is not a matter of justice but of love on the part of God based on the faith of Abraham, on God’s promise and on God’s plan to bless the whole earth through the seed of Abraham. Well, God has fulfilled this plan.
It is not a question of justice for God to bless Israel. God is always just. If I choose to love one person, this does not do injustice to another. It would be unjust of God had treated the Gentiles unfairly, but he did not do this. God has always been just, including to the Gentiles. To bless one is not to do an injustice to another unless one had promised beforehand to treat everyone exactly equally. This is not the case. Even if God had chosen to bless Israel for completely arbitrary reasons, this still would not have been an injustice to the Gentiles. But this is not what happened. God chose Israel, both because of the faith of Abraham, and because he had a plan to bless all people. In what way could this be an injustice.
Interestingly, in Romans chapters 10 and 11 there is a long and fairly difficult discussion between God and the Jews. If you read this you will see that the Jews are charging God with being unjust to them for offering salvation to the Gentiles. This is a sort of reverse of the argument you are making above. Paul is quite impatient with this kind of thinking. He tells the Jews that if God chooses to bless the Gentiles, they should be happy he has done so! The argument is a bit hard to follow, but look at Romans 11:13-24 and you will see that God is answering the charge of the Jews that he is unjust. His reply is that everything he has done has been in an effort to save as many as possible. If the salvation of the Gentiles makes the Jews jealous enough to return to him, that is fine with God. Similarly, if we Gentiles see the fact that the Jews were chosen and this drives us toward God, that is good too. The ultimate goal of God is to come into a relationship with as many as possible.
So, there is no injustice in God’s choice of Israel. It is about his love for ALL people, it about the faith of Abraham, and it is about his plan to bless all people through him.