The following is an excerpt from The MacArthur New Testament Commentary on Revelation 7.

And I heard the number of those who were sealed, one hundred and forty-four thousand sealed from every tribe of the sons of Israel: from the tribe of Judah, twelve thousand were sealed, from the tribe of Reuben twelve thousand, from the tribe of Gad twelve thousand, from the tribe of Asher twelve thousand, from the tribe of Naphtali twelve thousand, from the tribe of Manasseh twelve thousand, from the tribe of Simeon twelve thousand, from the tribe of Levi twelve thousand, from the tribe of Issachar twelve thousand, from the tribe of Zebulun twelve thousand, from the tribe of Joseph twelve thousand, from the tribe of Benjamin, twelve thousand were sealed. (7:4–8)These Jewish believers and evangelists are the firstfruits of Israel, which as a nation will be redeemed before Christ returns (Zech. 12:10–13:1, 8–9; Rom. 11:26). The 144,000 are not all Jewish believers at that time, but a unique group selected to proclaim the gospel in that day (cf. 12:17; 14:1–5). Despite the plain and unambiguous declaration of the text that the one hundred and forty-four thousand who are to be sealed will come from every tribe of the sons of Israel, many persist in identifying them as the church. They cite several New Testament passages that allegedly identify the church as Israel to support that interpretation. But the identification of Israel with the church in those passages is tenuous and disputed. Thus, they can offer no support for such an identification in the present passage. The fact is that “no clear-cut example of the church being called ‘Israel’ exists in the NT or in ancient church writings until A.D. 160. … This fact is crippling to any attempt to identify Israel as the church in Rev. 7:4” (Robert L. Thomas, Revelation 1–7: An Exegetical Commentary [Chicago: Moody, 1992], 476). Further, “such an attempt becomes even more ridiculous because it necessitates typological interpretation that divides the church into twelve tribes to coincide with the listing of Rev. 7:5–8, even with all the irregularities in that list” (Thomas, Revelation 1–7, 476). The term Israel must be interpreted in accordance with its normal Old and New Testament usage as a reference to the physical descendants of Abraham, Isaac, and Jacob. Nor is there any exegetical reason not to interpret the numbers 144,000 and 12,000 literally.