The Disciples are those who abide in Jesus after they say they believe Him.
Can't really say you believe someone if you don't do what He says.
Matthew.24:3 And as He sat upon the mount of Olives, the disciples came unto Him privately, saying, Tell us, when shall these things be? and what [shall be] the sign of Thy coming, and of the end of the world?
Matthew.28:16 Then the eleven disciples went away into Galilee, into a mountain where Jesus had appointed them. 17 And when they saw Him, they worshipped Him: but some doubted. 18 And Jesus came and spake unto them, saying, All power is given unto Me in heaven and in earth. 19 Go ye therefore, and disciple all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: 20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, [even] unto the end of the world.
Jesus says the message never changes. He taught the words the Father gave to Him, just as He says He did in John.12:28-50. Jesus says that we will believe on Him because the 11 Disciples will tell those words to us, John.17:20. Jesus says they will bear witness of Him because they were with Him from the beginning, John.15:26.
If it seems like common sense... well, sense must not be very common, these days.
John.6:37 All that the Father giveth Me shall come to Me; and him that cometh to Me I will in no wise cast out. 38 For I came down from heaven, not to do Mine own will, but the will of Him that sent Me.
Matthew.7:24 Therefore whosoever heareth these sayings of Mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock: 25 And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock. 26 And every one that heareth these sayings of Mine, and doeth them not, shall be likened unto a foolish man, which built his house upon the sand: 27 And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell: and great was the fall of it.
James.2:18 Yea, a man may say, Thou hast faith, and I have works: shew me thy faith without thy works, and I will shew thee my faith by my works.
Matthew.15:24 But He answered and said, I am not sent but unto the lost sheep of the house of Israel.
Matthew.4:18 and 21 = Peter, Andrew, James and John.
Matthew.9:9 = Matthew.
John.1:44 = Philip.
I've already done this work elsewhere, so it's easy to find out where Jesus got His Apostles. Apparently Jesus did exactly what He said He came to do... find and save the lost sheep of Israel, which are the 10-north-tribes.
The kingdom was divided and it still is, even today. It is incorrect to call that modern nation in Palestine by the name of the 10-north-tribes. In fact, Jesus made that point for us.
John.7:1 After these things Jesus walked in Galilee: for He would not walk in Jewry, because the Jews sought to kill Him.
John.1:11 He came unto his own, and His own received Him not.
Yeah... the goats in the church are the tares.