βIf the apostles picked a replacement for Judas when he died, why didnβt they pick a replacement for James when he was killed?β
We know that the Lord told the Twelve that βin the regenerationβ they would βsit upon twelve thrones, judging the twelve tribes of Israelβ in the kingdom of heaven (Matt. 19:28). So when Judas betrayed the Lord and took his life, it was necessary that he be replaced, as Peter explained in Acts 1:15-26.
But had the apostles replaced James when he was killed (Acts 12:1,2), there would beΒ thirteenΒ apostles in the resurrection and only twelve thrones on which for them to sit. Remember, James will rise in βthe first resurrectionβ (Rev. 20:5) to assume his throne with the rest of the Twelve, but Judas will not.
This is similar to how Job lost βseven sons and three daughtersβ (Job 1:2 cf. 1:18,19) and lots of livestock (1:3 cf. 1:14-17). Later, when βthe LORD gave Job twice as much as he had beforeβ (42:10), He doubled Jobβs original number of animals (42:12) but only gave him an additional βseven sons and three daughtersβ (42:13). You see, he hadnβt lost his familyΒ eternally. They will rise with him in the resurrection, where he will have twice as much family as he had while here on earth. And the Twelve hadnβt lost James eternally either, so there was no need to replace him. With the kingdom program in abeyence, a twelfth apostle would not be needed before the resurrection. source