2. The contextual differences between "ye" "them" and "all nations"
This context provides only three possible options as to the identity of those being authorized by Christ to carry out this command we call a commission.
1. "all nations"
2. "ye"
3. "them"
Those authorized to administer this commission cannot be "all nations" as they are the objects of the commission rather than the actors of it.
Those authorized to administer this commission cannot be "them" as they are the objects for baptism and instruction. These are those who received the gospel from among "all nations" but have not yet been baptized or instructed.
This is significant for several reasons. First, it leaves only "ye" and demands that those authorized are not among the "them" or those without baptism or instruction. The phrase "whatosver I HAVE commanded you" demands they have already been through this process prior to being authorized to carry out this commission. So these are not unbaptized or uninstructed administrators as the blind leading the blind would cause all to fall into the ditch. One cannot teach what they have not been taught.
The immediate antecedent for "ye" in this context is found in verses 16-17. At first appearance it would seem it refers only to "the eleven disciples." However, if one begins at verse 10 this command is given to more than the eleven disciples, but the women were told of this meeting place and they were instructed to tell "his disciples" (vv. 7-8) and "my brethren" (v. 10). Therefore, those as identified as "women" and "his disciples" and "my brethren" were all notified of this precise meeting place in Galilee. These are the same three categories used to describe the 120 in Acts 1:15-17.
Moreover, verse 17 says "some doubted" however, prior from leaving Jerusalem Christ appeared to all of the eleven apostles including the last doubting one Thomas. While on the way to this mountain in Galilee Christ appeared to Peter and those who went fishing with him confirming his love for them in spite of their failures. Finally, Matthew chooses to call them "disciples" rather than "apostles" in Matthew 28:16 as the commission was to reproduce disciples.
This context that the very same ones told of this meeting place in Matthew 28:7-10 (women, disciples, brethren) are the very same ones described in Acts 1:15-17 or the 120 including their ordained leadership (the eleven) and it some of these 100 besides the women and the eleven that doubted. Finally, Acts 1:21-22 demands that more had to be present as the qualification to fill the vacated office of Judas was that such a person IN ADDITION TO the 12 apostles had to be companying with them from the time of the baptism of John until his resurrection. Therefore, even though most of the texts where only the twelve are directly mention between Matthew 5-28:17 there had to be other disciples present which sets precedent that more were present than the eleven on this mount. In addition when Christ demanded "his apostles" to wait in Jerusalem for the baptism in the Spirit (Acts 1:2-5) it is the entire 120 who are obeying this command (Acts 1:15-17, 2:1) demonstrating there were more than just the apostles being addressed even though the text only mentions the apostles. This 120 is what the 3000 on Pentecost is "added unto" (Acts 2:40) and they are called "the church" (Acts 2:46). Finally, Acts 1:21-22 demonstrates there was a consistent assemblying with Christ during his whole public ministry and must have been so or else they could not have obeyed Matthew 28:20 which demands assembling for instruction in the past as the aorist tense "have" commanded demands.
However, regardless, those being authorized are not "all the nations" or unbaptized, uninstructed believers. Those authorized are previously baptized believers which assembled consistently with Christ under his instruction with other disciples as Acts 1:21-22 demands and that is the church addressed in Matthew 18:17 and is being addressed in Matthew 28:16-17 and which continued to assemble in Acts 1 and 2:1. He is addresseding a plural body of baptized believing disciples who "have" been habitually assembling together under his instruction (Acts 1:21-22) or what he calls "my church" (Acts 2:1,40,46).
This commission is not given to unbaptized and uninstructed Christians and therefore it is not being given to Christendom. It is given only to baptized believers in an observing assembled capacity.