Turn away from (5290) (hupostrepho from hupo = under + strepho = to turn, to change) means to turn back from or to return (go back to a location). Peter uses hupostrepho figuratively meaning these men made a definite turn back to (aorist tense = completed effective action in the past) a previous belief. The made a change to their former belief which describes the perversion and defection of the false teachers. They professed "the way of righteousness" and had access to the true teachings of Scripture ("the holy commandment") but by their lives they demonstrated that they had chosen to reject Christ so they turned back to the Christ-rejecting, godless belief.. Friberg - intransitively in the NT turn back, return; with eis and the accusative of place or state be again in, return to (Luke 1.56); with apo, and the genitive return from (Lk 4.1); with ek and the genitive turn away from (2P 2.21) NAS Usage: return(6), returned(22), returning(3), started back(1), turn away(1), turned back(1), went back(1). Hupostrepho - 35x in 35v - Luke 1:56 And Mary stayed with her about three months, and then returned to her home. Luke 2:20 The shepherds went back, glorifying and praising God for all that they had heard and seen, just as had been told them. 43 and as they were returning, after spending the full number of days, the boy Jesus stayed behind in Jerusalem. But His parents were unaware of it, 45 When they did not find Him, they returned to Jerusalem looking for Him. Luke 4:1 Jesus, full of the Holy Spirit, returned from the Jordan and was led around by the Spirit in the wilderness 14 And Jesus returned to Galilee in the power of the Spirit, and news about Him spread through all the surrounding district. Luke 7:10 When those who had been sent returned to the house, they found the slave in good health. Luke 8:37 And all the people of the country of the Gerasenes and the surrounding district asked Him to leave them, for they were gripped with great fear; and He got into a boat and returned. 39 "Return to your house and describe what great things God has done for you." So he went away, proclaiming throughout the whole city what great things Jesus had done for him. 40 And as Jesus returned, the people welcomed Him, for they had all been waiting for Him. Luke 9:10 When the apostles returned, they gave an account to Him of all that they had done. Taking them with Him, He withdrew by Himself to a city called Bethsaida. Luke 10:17 The seventy returned with joy, saying, "Lord, even the demons are subject to us in Your name." Luke 11:24 "When the unclean spirit goes out of a man, it passes through waterless places seeking rest, and not finding any, it says, 'I will return to my house from which I came.' Luke 17:15 Now one of them, when he saw that he had been healed, turned back, glorifying God with a loud voice, 18 "Was no one found who returned to give glory to God, except this foreigner?" Luke 19:12 So He said, "A nobleman went to a distant country to receive a kingdom for himself, and then return. Luke 23:48 And all the crowds who came together for this spectacle, when they observed what had happened, began to return, beating their breasts. 56 Then they returned and prepared spices and perfumes. And on the Sabbath they rested according to the commandment. Luke 24:9 and returned from the tomb and reported all these things to the eleven and to all the rest. 33 And they got up that very hour and returned to Jerusalem, and found gathered together the eleven and those who were with them, 52 And they, after worshiping Him, returned to Jerusalem with great joy, Acts 1:12 Then they returned to Jerusalem from the mount called Olivet, which is near Jerusalem, a Sabbath day's journey away. Acts 8:25 So, when they had solemnly testified and spoken the word of the Lord, they started back to Jerusalem, and were preaching the gospel to many villages of the Samaritans. 28 and he was returning and sitting in his chariot, and was reading the prophet Isaiah. Acts 12:25 And Barnabas and Saul returned from Jerusalem when they had fulfilled their mission, taking along with them John, who was also called Mark. Acts 13:13 Now Paul and his companions put out to sea from Paphos and came to Perga in Pamphylia; but John left them and returned to Jerusalem. 34 "As for the fact that He raised Him up from the dead, no longer to return to decay, He has spoken in this way: 'I WILL GIVE YOU THE HOLY and SURE blessings OF DAVID.' Acts 14:21 After they had preached the gospel to that city and had made many disciples, they returned to Lystra and to Iconium and to Antioch, Acts 20:3 And there he spent three months, and when a plot was formed against him by the Jews as he was about to set sail for Syria, he decided to return through Macedonia. Acts 21:6 Then we went on board the ship, and they returned home again. Acts 22:17 "It happened when I returned to Jerusalem and was praying in the temple, that I fell into a trance, Acts 23:32 But the next day, leaving the horsemen to go on with him, they returned to the barracks. Galatians 1:17 nor did I go up to Jerusalem to those who were apostles before me; but I went away to Arabia, and returned once more to Damascus. Hebrews 7:1 For this Melchizedek, king of Salem, priest of the Most High God, who met Abraham as he was returning from the slaughter of the kings and blessed him, 2 Peter 2:21 For it would be better for them not to have known the way of righteousness, than having known it, to turn away from the holy commandment handed on to them. Hupostrepho - 12v in the non-apocryphal Septuagint - Ge 8:7, 9; 43:10; Ex 32:31; Josh 2:23; Jdg 3:19; 7:15; 14:8; 21:23; Esther 6:12; Pr 23:5; Da 6:18. The Septuagint Lexicon says hupostrepho usually means to return, to turn back. J Vernon McGee would sometimes conclude his messages with this statement Friends, if you came in here today unsaved and you walk out of here unsaved, I am the worst enemy that you have ever had, because you have heard the gospel and you can never go into the presence of God and tell Him that you have never heard the gospel. You have heard it, and it will be worse for you when God pronounces judgment than for any heathen in the darkest part of the earth today. John MacArthur notes one important point Peter implies is that these false teachers were not made outside Christianity. They are always bred in the church, half in and half out; but eventually they reject the truth and try to seduce others in their attempt to fulfill their self-gratification Life Application Bible has a great illustration of the final "end zone" of these deceived deceivers Pity the football player who runs a full sprint into the wrong end zone, scoring against his own team, like USC’s ““Wrong-Way” Riegels at the 1929 Rose Bowl. No one ever forgets that kind of mistake. It lives in history books. Peter pities those who know God, then turn away. To have the truth but follow evil is as low as life gets. If you are discouraged, tempted to quit, or running with the opposition, God wants you back. Find a Christian friend who will hear you out, pray with you, and become your spiritual coach, helping clarify your goals through the confusion and doubt." 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