I've read some texts and versions of the Bible using the capitalized form of Gentile and others using just a lowercase version. I couldn't find any standards on its usage.
Gentiles are not a specific group. They are everyone who is not Jewish. They do not represent any particular ethnicity, belief system, national group, or ideology — other than being not Jewish.
Words with a similar scope are "pagan," "heathen," and "foreign." Even though "pagan" and "heathen" could be taken as representing a very coarsely defined type of religion, they do not represent distinct groups or belief systems. I think most people would agree that these words should not be capitalized.
The online dictionaries that I checked show "gentile" as a lowercase word, in contrast to other proper nouns such as "Jew" that they display capitalized:
- Merriam-Webster (but says, "often capitalized")
- Oxford Living Dictionaries
- Cambridge Dictionary
Based on this evidence, it's safe to treat "gentile" as a standard lowercase word.
Quoted from wikipedia :
The term Gentile (from Latin gentilis, by the French "gentil", female: "gentille", meaning of or belonging to a clan or tribe) refers to non-Israelite peoples or nations in English translations of the Bible.
Latin and subsequently English translators selectively used the term gentiles when the context for the base term "peoples" or "nations", Hebrew, גוי (goy) and נכרי (nokhri) in the Hebrew Bible and the Greek word ἔθνη (éthnē) in the New Testament, indicated non-Israelite peoples or nations. The term gentiles is derived from Latin, used for contextual translation, and not an original Hebrew or Greek word from the Bible.
Following Christianization of the Roman Empire, the general implication of the word gentile became "non-Jew".
In short when we are referring to the "non-Jew" people, like a quality, it is lower-cased. When we are speaking about group of people - non-Israelite peoples, it is capitalized.
This is more of a sociological and historical answer. "Gentile," when spoken or written by a Jew, is no more a proper noun than if he were to use "foreigner" since all it refers to is non-Jews and we do not capitalize "non-Jews" or "foreigners." So, if some style manual advises capitalizing "gentile," a Jew, in order to assimilate, would probably capitalize it, even while realizing how silly the convention is. Likewise, "Pharisee" is defined in many dictionaries as "hypocrite" although that is hardly what it meant in biblical times and the early centuries CE when there were Pharisees. The way it is sometimes used in the New Testament is in criticizing Pharisees--i.e. it is an opinion. But we do not define the Democratic or Republican party by the other party's criticisms of it. The Pharisees were a sect or party within Judaism.
The Gentiles are described in the Book of Genesis, Chapter Ten (10:5) with capitalization...K.J.V. The Gentiles are also mentioned in Zechariah, Chapter One (1:15,21)...K.J.V., although verse 15 is written as "Heathen" in the K.J.V.version of the Bible, in other versions of the Bible "Heathen" is referred to as "Gentiles" and "Pagans" are considered to be non-Israelite. Also the New Testament talks about "A people without GOD"... Ephesians Chapter Two (2:11-12)...K.J.V. No matter whose tribe we came from, thank GOD for JESUS... "For all have sinned, and come short of the glory of God"- Romans Chapter Three (3:23)...K.J.V.
I don't buy this. Gentile, like Semite, is a proper noun. I note that Semite is always capitalized, yet Gentile should not always be according to some. I think this should be a consistent use and be capitalized when used as a proper noun, and not, when used as an adjective. I find also that every Bible translation that I looked up (KJV, NKJV, NIV, NAB, ESV, NLT) all follow the same principle in which the word, Gentile, as a proper noun is capitalized.
If you are going to capitalize proper nouns, and capitalize other proper nouns associated with the use of the proper noun of "Gentile," like "Semite," and "Jew," then you need to be consistent with all such usage. I think that the Bible translators recognized this.
In English, it is correct to capitalise a person's nationality.
As 'Gentile' is a translation of the word 'goy' which literally means 'Nation', it seems logical that the word would refer to one or many non-Jewish nationalities, and although not referring to a specific nationalitiy, should be treated as a nationality nonetheless, in the same way as 'African' or 'Asian' would be.
I would suggest that capitalisation is both correct and polite, and not doing so could cause offense.