The order of the four Gospels in the Bible represent the order of the four steps or four laws of salvation: Matthew = Repentance. Mark = Faith for the forgiveness of sins. Luke = Works. John = Remaining or Abiding.
This may have been referred to by Methodius in 290 A.D. who said, "Four Gospels have been given because God has four times given the Gospel to the human race. And He instructed them by four laws."
The pattern which reveals this order in each book is: 1. The first words of Jesus in each of the four Gospels. 2. The first words of Jesus of his first occasion of public preaching in each book. 3. The last command, or the last instructions of Jesus in each book. 4. Who or what each author or writer of each book is. 5. The content of the greatest proportion of each book.
Matthew = Repentance: The first words of Jesus in the book of Matthew are about immediately ending sins you can repair now, (the word repent literally means to repair wrongs) & commitment and intention in the future, ("becometh"), to "fulfill all righteousness", 3:15, this is the purpose of repentance. Repentance requires works Luke 3:8, Acts 26:20. See point 1 in link 10 of this site. The first words of Jesus when he preached in public for the first time in Matthew was "Repent", 4:17. The last words in Matthew by Jesus was a command to the Apostles to teach the world " whatsoever I have commanded you", 28:20. The "whatsoever" is revealed in the content of the book of Matthew: there are over 200 teachings on how to live right in the book of Matthew, more than the other 3 Gospels. The words "righteousness" and"unrighteousness" appear more times in the book of Matthew than in the other 3 Gospels combined! Matthew himself was a repentant tax collector, ( publican means tax collector ). Tax collectors in the book of Matthew were of a negative reputation, needing repentance, 18:17. None of the above characteristics of the book of Matthew are true of the books of Mark, Luke or John.
Mark = Faith: The book of Mark represents the second step, or law, for salvation: Faith to receive the grace and mercy of God for the forgiveness of sins. "Gospel" means "God's good news about the forgiveness of your sins". The "good news" is that God will forgive your sins. We know that the book of Mark represents this because is explicitly says so, Mark 1:1. Notice something first, Mark 1:1-4 mentions that the "beginning" of the "Gospel" is "repentance", that the first step or the first law for salvation is to repent of your sins. The first words of Jesus in the book of Mark are to "repent", "believe", or to have faith, in the "Gospel", 1:15. Verse 14 says that Jesus came "preaching" the "Gospel", so the first words Jesus said in Mark, which was also the first words of His first occasion of public preaching in Mark, was "repent", and "believe" the "Gospel". The last words of Jesus in the Gospel of Mark was the command to preach the "Gospel", that he that "believes" will be "saved", 16:15,16. Note here though He does not mention "repent", that's because the main point of Mark is to "believe" the "Gospel", to have faith for the forgiveness of your sins. The largest portion of the book of Mark has to do with Jesus' suffering, crucifixion and resurrection, which are the means for forgiveness of your sins. Mark was a servant: Acts 12:12,25. Acts 15:37,39. 2 Timothy 4:11. He was the servant also of the Apostle Peter and wrote the book of Mark according to Peter. Mark was a servant and therefore represents Jesus who was our suffering servant. The fact that Jesus was our suffering servant is the means for our forgiveness of sins, which we obtain by Faith. None of the above facts of the book of Mark are true of the other 3 Gospels, except in Luke the first words of his public preaching does mention to preach the "Gospel", but in Luke that is just one of many other things mentioned in his first public preaching, where in Mark just repentance and the Gospel are mentioned.
Luke = Works: The book of Luke represents the third step or law for salvation: Works. Luke 1:74,75 gives us our purpose in life, serving God in holiness and righteousness. The first words of Jesus in the Gospel of Luke was that his purpose was to do his Father's works, 2:49. The first words of Jesus' first public preaching was his purpose on earth to do good works, 4:18. The last command or instruction in the book of Luke was to the Apostles to tarry for power from on high, which came by the Holy Ghost, 24:49. The purpose of the power was to do the work Jesus wanted them to do, Acts 1:8. The book of Acts was also written by Luke. This power is also for help to do works in general, Galatians 5:16. Luke explicitly states that Jesus was noted for his "deeds", and his word, which is part of deeds. Jesus does more works in Luke than in the other 3 Gospels . Luke was a physician, Col 4:14. A physician heals, which is a work. Healing on the Sabbath was forbidden by the Jews because it was considered "work", Matt 5:15-17. Matt 12:10. Mark 3:15. Luke 6:7. Luke 14:3. The man Luke represents the third step or law for salvation: Works. None of the above facts about the book of Luke are true about the books of Matthew, Mark or John. Note, after the day of Pentecost the gift of healing was available to the Church. There are no words of relying on a physician in the Bible after the day of Pentecost, or in early church history. There are no words prohibiting the use of a physician in the Bible either.
John = Remaining, or Abiding: The book of John represents the fourth step or law for salvation: to Remain, or Abide, in Faith and Works. This is also called in the Bible "following" Jesus, which includes both faith and works. The very first event and first words of Jesus in the Gospel of John seem at first to be extremely trivial and unimportant John 1:38,39: "Then Jesus turned, and saw them following, and saith to them, What seek ye? They said unto him, Rabbi, (which is to say being interpreted, Master) where dwellest (margin notes KJV "or abideth") thou? He saith unto them, Come and see. They came and saw where he dwelt, and abode with him that day: for it was about the tenth hour. (Margin notes in the KJV for tenth hour say, "That was two hours before night"). Interesting that the first words of Jesus in the book of John have to do with where he lived. In fact it is a symbol or type of the fact that we need to abide with Jesus, or remain with Him. Note, it was two hours before "night". "Night" in the Bible is often a symbol for the time when no one has a chance to be saved. The first words of the first occasion of public preaching by Jesus in the book of John have to do with remaining so you won't be lost. John 12, "When they were filled, he said unto his disciples, Gather up the fragments that remain, that nothing be lost." In other words, after you have been filled with Jesus, He or his angels, will gather you, if at the time you are remaining in Him, then you won't be lost, or missing your chance for heaven, or eternal life. The last words and command of Jesus in the book of John are to follow Him and to tarry for Him, and that the ones Jesus loves are the ones following Him, John 21:19-22. The words "abode" and "remain" appear in the book of John more than the other 3 Gospels combined! There is also more teaching on remaining than in the other 3 Gospels combined! John has a whole chapter worth just on the need to remain, and explicity remaining in his "commands", John 14:15 through 15:16 and 18:21. The following is really amazing: Who was John? John was the only Apostle who "remained" with Jesus all the way during Jesus' arrest and interrogation, and till the end. Peter was following for a while, but not the whole way, and then had to become "converted" after, John 18:15,16. Luke 22:32. John wrote the book of John, 13:23. 21:20-24. The man John represents the fourth step or law in salvation: Remaining, or Abiding. None of the above facts about the book of John are true about the books of Matthew, Mark or Luke.
Some chapters or passages in the Bible have all 4 steps, or Laws, of Salvation: One example is Philippians chapter 3: Repentance vs.7,8. Faith vs. 9. Works vs. 10,11. And Abiding or Continuance vs. 12-21. Paul would not have to repent for doing "the righteousness of the Law" mentioned in the list in vs. 5 and 6 unless he thought that it would benefit him without Jesus as he knew about Jesus and had rejected him, but he would have to repent of everything else in that list.