Consider this response to a similar question in the Watchtower mag of 7/1/72.
Questions From Readers
Large numbers of Christians are said to have been put to death during the Roman persecution in the first few centuries of the Common Era. How, then, is it possible for thousands in this century to have been called to become part of the body of Christ composed of only 144,000 persons?—U.S.A.
"There are historical indications that many Christians were bitterly persecuted, even killed, in the first few centuries. However, it should be remembered that, in itself, a martyr’s death did not give a person merit before Jehovah God nor did it guarantee membership in the heavenly kingdom. Many persons, even in recent times, have been willing to die for a cause, religious or otherwise. A person’s claiming to be a Christian and even dying for his belief does not in itself mean that he is an approved servant of Jehovah God. As the apostle Paul wrote to the Corinthians: “If I give all my belongings to feed others, and if I hand over my body, that I may boast, but do not have love, I am not profited at all.” (1 Cor. 13:3) It is not death, but faithfulness to the very death, that determines whether an individual will receive “the crown of life.”—Rev. 2:10.
Thus the fact that today there is still a remnant of the 144,000 on earth would show that down to this twentieth century fewer than 144,000 finished their earthly course in faithfulness.
While some persons may be inclined to think that more persons must surely have been involved even as far back as the early centuries of the Common Era, actual proof to this effect is completely lacking. Today it is impossible even to establish how many persons were killed, much less the number of those who proved faithful to death. “We have practically but few facts to go upon,” writes Frederick John Foakes-Jackson in the book History of Christianity in the Light of Modern Knowledge. He further states: “The testimony to the persecution by Nero is recorded by two Roman historians, Tacitus and Suetonius, both of whom were very young when it occurred, and wrote in mature life. There is no contemporary Christian document describing it, though it may be alluded to in the book of Revelation. . . . Tertullian at the end of the second century is our authority that Nero and Domitian, because they were the two worst emperors in the first centuries, persecuted the Christians.” Early in the third century C.E., Origen (a Christian writer and teacher) observed: “There have been but a few now and again, easily counted, who have died for the Christian religion.”
Much that has been written about Christian martyrs is embellished by tradition and therefore unreliable. For example, the martyrdom of Polycarp of the second century C.E. is described in Fox’s Book of Martyrs as follows: “He was . . . bound to a stake, and the #### with which he was surrounded set on fire, but when it became so hot that the soldiers were compelled to retire, he continued praying and singing praises to God for a long time. The flames raged with great violence, but still his body remained unconsumed, and shone like burnished gold. It is also said, that a grateful odour like that of myrrh, arose from the fire, which so much astonished the spectators, that many of them were by that means converted to Christianity. His executioners finding it impossible to put him to death by fire, thrust a spear into his side, from which the blood flowed in such a quantity, as to extinguish the flame. His body was then consumed to ashes, by order of the proconsul lest his followers should make it an object of adoration.”
Whatever the source of Fox’s information, manifestly little of this account is truly historical. Nevertheless, if the allusion to the adoration of the remains of Polycarp is to be viewed as indicating the existence of relic worship among professed Christians of the second century C.E., this would be additional evidence that many at that time were not faithful worshipers of Jehovah God. Christians were under command to “worship God,” not relics. (Rev. 19:10) In fact, idolaters are among those specifically named in the Scriptures as unfit to inherit the Kingdom.—1 Cor. 6:9, 10."