There will martyrs of Christ in all nations in the end times, how come that those must be all Israelites? Besides, if those are the 144,000, haven't they been sealed in chapter 7?
They are all Israelites because the beast that received a deadly wound and was healed is the Israeli government.The deadly wound was healed in 1948.
Revelation 20:6
Blessed and holy are those who share in the first resurrection. The second death has no power over them, but they will be priests of God and of Christ and will reign with him for a thousand years.
Revelation 20:6 is the fulfillment of Exodus 19:6
Exodus 19:6
And ye shall be unto me a kingdom of priests, and an holy nation. These
are the words which thou shalt speak unto the children of Israel.
In about a year to year and a half ,a second beast will appear in Israel.It is at that time those saints in Israel will be persecuted and killed as Jesus was.
Mathew 23
33 Ye serpents, ye generation of vipers, how can ye escape the damnation of hell?
34 Wherefore, behold, I send unto you prophets, and wise men, and scribes: and some of them ye shall kill and crucify; and some of them shall ye scourge in your synagogues, and persecute them from city to city:
35 That upon you may come
all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias son of Barachias, whom ye slew between the temple and the altar.
36 Verily I say unto you, All these things shall come upon this generation.
37 O Jerusalem, Jerusalem, thou that killest the prophets, and stonest them which are sent unto thee, how often would I have gathered thy children together, even as a hen gathereth her chickens under her wings, and ye would not!
38 Behold, your house is left unto you desolate.
39 For I say unto you, Ye shall not see me henceforth, till ye shall say, Blessed is he that cometh in the name of the Lord.