Judaism and Bani Israel have concept of Gentile to represent the pagans and Idolaters with a corpus of rules dealing with them, So does Christianity inherit this concept? If yes where ? and Are Jews considered to Be gentiles by Christians as its known that Jews consider the Christians to be Gentiles and Avodah Zarah?
The term Gentile in the Bible simply means non-Jew or non-Hebrew. In Old Testament times, the Hebrews called the other non-Hebrews as Gentiles and in the New Testament, non-Jews are Gentiles.
In the New Testament, Paul was famous for preaching to the Gentiles. Because Paul was a Jew, he was zealous for his own people and preached the gospel mostly to the Jews first. But later, as his own people rejected him, his focus shifted towards the Gentiles.
According to New Testament, anyone who is not a Jew is a Gentile, whether he is a Christian or not. And believe it or not, most of the users in this site are Gentile Christians.
Some recent new Christian sects call all non-Christians including Jews as Gentiles but it's not biblical. All non-Jews are Gentiles but non-Jews who are non-Christians are more appropriate to be referred to as Pagans, Heathens, Infidels or simply non-believers, depending on the target.
Most branches of Christianity see Jesus, the Son of God, as the Jewish Messiah in fulfillment of Jewish prophecies and foreshadowing in the Jewish Scriptures.
God foretold, though, that the Seed of Abraham would be a blessing to all people--every tribe, tongue and nation. The apostle Paul specifies that the gospel is to the Jew first and also to the Gentile.
Jesus was born to a Jewish mother in a Jewish city in the land of the Jews. His first followers were Jews and the earliest growth of the church was among Jews (Acts 1-7).
So, non-Jewish believers in Jesus identify themselves as the Gentiles--the ones who were once "outside" but who are now "included". We see ourselves as the "other sheep" of which Jesus spoke when He was addressing a Jewish audience.
Messianic Jews--Jews who recognize Jesus as their Messiah--oftentimes consider themselves "completed Jews", or Jews that recognize the Messiah that God foretold and sent into the world.
So, in conclusion, non-Jewish Christians see themselves as the Gentiles that God blessed through Jesus, who is both the God of Abraham and the descendant of Abraham in the flesh.
In Christianity, there are two sets of people, but one group is not excluded or held to different standards than the other. There are:
God's people are identified solely by their faith in Jesus Christ as savior/redeemer. By faith we become part of the same family. With those who have faith in His Son, God had made an everlasting covenant to bring them into His kingdom as join heirs with Christ himself.
Everybody else can be labeled however you like (e.g. pagans, non-Christians) but it all boils down to the same thing. The "rules" that apply to them are simple:
In the Teachings of Jesus and the writings of the Apostles, there is a common theme of the world that represents an established system that is separate from and foreign to Messiah.
This chief (αρχε "principle" or "foremost") of the world is also mentioned by Paul,
John clarifies the spirit to which Paul refers in his own teaching on the world.
The world is a system which in the mind of the Christian is similar to the notion of Avoda Zarah among Jews. Avoda Zarah translates to "foreign worship" or "idolatry." In Romans, Paul equates men operating according to the spirit of error with idolaters,
"An image in the form of corruptible man and of birds and four-footed animals and crawling creatures" is an idol. Paul continues speaking of those who suppress the truth,
These men who operate according to the spirit of the world, the spirit of error, are then by definition idolaters, which is Avoda Zarah. Those who teach lies according to the spirit that is in the world are antichrists, which translates literally from the Greek to the counter-anointed.
The world has no part in Messiah or in the Kingdom of God, because the world rejects and hates the things of God. This is how Christians are taught to see the world in practice: