Q: Why did God require the Jews to be circumcised? Was it for health reason? And why is this no longer required of God's people today? What I am really asking is, what was circumcision all about?
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A: That is an interesting question! Why did God give Abraham the law regarding circumcision, which was mandatory not just for Abraham and his natural offspring, the Jews, but also for every male slave of theirs? This is what Insight On the Scriptures says regarding the law of circumcision:
 

"Jehovah God made circumcision mandatory for Abraham in 1919 B.C.E., a year before Isaac’s birth. God said: 'This is my covenant that you men will keep . . . Every male of yours must get circumcised.' Every male in Abraham’s household of both his descendants and dependents was included, and so Abraham, his 13-year-old son Ishmael, and all his slaves took upon themselves this 'sign of the covenant.' New slaves brought in also had to be circumcised. From then on, any male of the household, slave or free, was to be circumcised the eighth day after birth. Disregard for this divine requirement was punishable by death.—Ge 17:1, 9-14, 23-27 (it-1 p. 469 Circumcision)

Note that Abraham was given the law of circumcision after Abraham had already been dwelling in the land of Canaan for 24 years. In other words, God had concluded his covenant with Abraham—which included giving him the promised land; to make a great nation out of him; and to have all the nations of the earth bless themselves by means of his seed—while he was still uncircumcised. In fact, by the time Abraham was instructed to become circumcised he had already become father to his son Ishmael, by his slave girl Hagar, who was by now 13 years old. (Gen. 12:1-7; 15:1, 5-7, 18; 22:17,18) Why is this of significance? Because, as Paul explains, the Abrahamic covenant guaranteed that the promised seed would come through Abraham's son Isaac, and would prove to be for the blessing of all the nations, not just for the Jews; whereas circumcision was added to the covenant, "as a sign of the covenant" between God and Abraham and his offspring alone, because the Messiah would be born in Abraham's lineage. (Rom. 4:3, 9-12; 9:6-8; Gal. 3:7-9, 14-18)

Abraham received the law of circumcision when he got to be ninety-nine years old, at which time God changed his name from Abram to Abraham, "because," as God told him, "a father of a crowd of nations I will make you. And I will make you very, very fruitful and will make you become nations, and kings will come out of you." (Exodus 19:6; Rev. 1:6; 5:10; 20:6) It was at this time that God commanded Abraham to become circumcised, saying: "As for you, you are to keep my covenant, you and your seed after you according to their generations. This is my covenant that you men will keep, between me and you men, even your seed after you: Every male of yours must get circumcised. And you must get circumcised in the flesh of your foreskins, and it must serve as a sign of the covenant between me and you." Every male born into Abraham's household, and even every man purchased as a servant, was to be circumcised. Indeed, God said that every male who would not get circumcised "must be cut off from his people. He has broken my covenant." (Gen. 17:1-14)

The importance of this command becomes clear when we understand the purpose of the law regarding circumcision, for it was not by coincidence that God also revealed to Abraham that by the same time the following year he was going to become father to a son, whom he was to call Isaac. Abraham and all the men of his household promptly complied and were circumcised. It was shortly after Abraham's circumcision, after he had time to heal, that he had relations with Sarah and conceived Isaac. (Rom. 9:7; Heb. 17,18) And in fulfillment of God's promise, one year later Isaac was born, when Abraham was already a hundred years of age, and his wife ten years younger. (Gen. 17:15-27; 18:9-14; 21:2-5)

Through Isaac, and Abraham's grandson Jacob, Abraham became a great nation; and the promised seed arrived at God's appointed time, almost two thousand years after Abraham's circumcision. (Matt. 1:1-16; Luke 3:23-34; Rom. 4:16-25; Gal. 3:16) John the Baptist pointed this one out to the people when Jesus came to be baptized, telling the Jews: "See, the Lamb of God that takes away the sin of the world." The promised seed, the Messiah, proved to be "God's only begotten Son," who came down from heaven and "became flesh and resided among us." (John 1:14, 29-34; 3:16; 8:39-47)

Reflect for a moment: How can an imperfect man born in sin, like Abraham, become the forefather of the "Son of God," holy, born perfect without sin? (John 6:69) We know that Adam could not pass on to his offspring the perfection that he lost upon his rebellion in the Garden of Eden. It is as Job said: "Who can produce someone clean out of someone unclean? There is not one." (Job 14:4; Eccl. 7:20; Rom. 3:23) A man born in sin can only pass on to his offspring his own sinfulness. (Psalms 51:5) Therefore, in order to make it possible for the promised seed to "come out of the loins" of Abraham, Jehovah required that Abraham and all his future male descendents, anyone who might possibly marry into the lineage leading to the Messiah, be circumcised, that is, have their reproductive powers "sanctified" by the removal of the foreskin. (Gen. 35:10-12; Ex. 12:44; Lev. 12:1-4; compare Lev. 19:23) This would yield a small amount of blood, because as Paul explains: "Yes, nearly all things are cleansed with blood according to the Law." According to the Law, it was blood that atoned for any sins. (Heb. 9:22; Lev. 17:11; compare Exodus 4:24-26) Accordingly, it was by circumcising the flesh, which drew blood (though minimal), that God cleansed the lineage from which the Messiah would be born by holy spirit, thus keeping it sanctified, holy. (Lev. 19:2; Matt. 1:18-21) Since all of God's servants were under the Law of circumcision (it became part of the Mosaic Law), including non Israelites who became proselytes, it prevented uncircumcised persons from contaminating the lineage.

Of note is the fact that Abraham was not required to get circumcised before he fathered Isaac, to whom belonged the promises. For example, he was not circumcised on account of his previous son Ishmael by Hagar, since Ishmael had no share in the ancestry leading to the Messiah. And once Jesus had arrived, there was no longer any need for circumcision; something that many of the Jews, who had become Jesus' disciples, failed to understand, not having grasped the significance of it. In fact, as Paul argued many times, continuing to practice circumcision according to the Law amounted to denying that the Messiah had arrived. (Acts 15:1, 5; Gal. 5:2,3)

No, it was not for any health reason that the law of circumcision was given to the Jews. Circumcision served "as a sign of the covenant" that Jehovah made between himself and Abraham, which covenant promised that God would multiply Abraham's seed "like the stars of the heavens and like the grains of sand that are upon the seashore." And from among this cleansed people the promised seed the Messiah would come, by means of whom "all the nations of the earth will certainly bless themselves." (Gen. 17:11; 22:17,18; Gal. 3:7-9) Circumcision was not a separate, distinct covenant! It was a necessary "sign of the covenant" for the purpose of keeping Abraham's lineage throughout the many generations sanctified, that is, holy, until the promised Messiah arrived. This further helps us to better appreciate why the nation of Israel needed to keep itself separate from any contamination due to intermarriage with uncircumcised people of the nations. (Compare Gen. 34:8,9, 13-22; Acts 10:28, 45; 15:5-9)

The Bible speaks of another sort of circumcision, a figurative "circumcising of the heart," that is vital for God's people today. Moses told the assembled Israelites, as they were poised to enter the promised land: "And you must circumcise the foreskin of your hearts and not harden your necks any longer." (Deut. 10:16; see Jer. 4:4, 14) This figurative circumcising involves the removal of all uncleanness and unrighteousness from our hearts, which grants us a clean standing before God; and which is made possible by our faith in the "blood of the covenant." (Matt. 26:27,28; 2 Cor. 7:1) The prophet Daniel foretold regarding God's people, that in the time of the end "many will cleanse themselves and whiten themselves and will be refined. And the wicked ones will certainly act wickedly, and no wicked ones at all will understand; but the ones having insight will understand." (Dan. 12:10;  Jer. 4:4; Rom. 2:28,29) Jehovah will have a cleansed people who will survive the coming great tribulation. He views them as righteous, "dressed in white robes." (Rev. 7:9,10, 13-17; 3:4,5; Isa. 61:10)
 

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