Why did Judas have to be replaced to make twelve apostles in Acts 1: 21–26 but not James in Acts 12: 2?

We read that the Lord “appointed twelve that they might be with him, and that he might send them to preach” (Mark 3: 14). These twelve were given “power over unclean spirits, so that they should cast them out, and heal every disease and every bodily weakness” (Matt. 10: 1)—the signs of the Kingdom (see Is. 35: 5, 6). They were sent out with the charge “Go not off into [the] way of [the] nations, and into a city of Samaritans enter ye not; but go rather to the lost sheep of the house of Israel” (Matt. 10: vs 5, 6). The appointment of twelve, for the proclamation of the Kingdom of the heavens to Israel, corresponded to the number of the twelve tribes. It had nothing to do with the Assembly (or Church), which as yet was not revealed in the ways of God. Later, after the concept of the Assembly had been made known (see Matt. 16: 18), the Lord said “ye who have followed me, in the regeneration when the Son of man shall sit down upon his throne of glory, ye also shall sit on twelve thrones, judging the twelve tribes of Israel” (Matt. 19: 28). The regeneration spoken of is the new state of things introduced when the Lord returns in power (see Acts 3: 20, 21). Matt. 19: 28 marks out the place that the twelve apostles will occupy in relation to Israel in “the habitable world which is to come” (Heb. 2: 5) and again is entirely independent of the place they have in the Assembly.

   Accordingly, when the defection and betrayal of Judas fulfilled the prophetic words of Ps 69: 25 and Ps 109: 8, a replacement was sought by prayer and casting lots, a practice not out of step with the law (see Lev. 16: 8; Num. 26: 55). The candidate for this office had to be fully identified with the Lord’s earthly ministry (see Acts 1: 21, 22) which was largely connected with the Kingdom as given in the Synoptics. When Peter preached on the day of Pentecost, the new concept of the Assembly did not go beyond the idea of a called–out company from Israel. If the nation had repented, the Lord would have returned (see Acts 3:19–21). In view of this, a replacement for Judas had to be chosen so that Matt. 19: 28 could then be satisfied. Although James the brother of John was later “slain with the sword” (Acts 12: 2) there was no such requirement as his membership of the twelve in connection with Israel in the world to come was not affected by his murder.

   This brings us to the Scriptures in Revelation. These are set in a section (Rev. 21: 9–22: 5), which describes, in the world to come, “the holy city, Jerusalem, coming down out of the heaven from God, having the glory of God” (v10). In keeping with the symbolism of a city in Scripture, this city will be  the centre of administration in the millennium and accordingly its description involves the copious use of the number twelve—the number of divine government or administration in the Bible.

   Now nearly all of the Revelation is built upon Scriptures from the OT. So when we read that this city had “a great and high wall; having twelve gates, and at the gates twelve angels, and names inscribed, which are those of the twelve tribes of [the] sons of Israel” (Rev. 21: 12), it comes as no surprise—for Ezekiel had prophesied of a city saying “And the gates of the city shall be after the names of the tribes of Israel” (Ez. 48: 31). While the general thought of a gate is that of entrance, the first mention of the word gate in the Bible (often of instructive significance) is in Gen. 19: 1. Comparing this verse with v9 shows us that a city gate is the place of judgment (see also Ruth 4: 11). Israel will have her place in administrative judgment in the world to come (see Is. 60: 3, 10–14) under the authority of the twelve apostles (see Mat. 19: 28). Finally, we are told that this city has “twelve foundations, and on them twelve names of the twelve apostles of the Lamb” (Rev. 21: 14). As the gates had names inscribed, so do the foundations of the wall. Name in Scripture indicates character, renown and authority depending on the context. On a simpler basis, a name is a means of identification. The stipulation in the choice of the replacement of Judas in Acts 1: 21, 22 was “that of the men who have assembled with us all [the] time in which the Lord Jesus came in and went out among us, beginning from the baptism of John until the day in which he was taken up from us, one of these should be a witness with us of his resurrection”. The foundations for the city’s walls are identified with those twelve who were fully conversant with the Lord’s Kingdom ministry during His time on earth. Paul, for example, did not possess these qualifications. Yet again, all this has to do with the Kingdom in the world to come and has nothing to do with the Assembly directly as such.