Let me know if you see the contradiction (of non-osas) in the Synoptic Gospels. God bless.
Matt 13:21 (does not use the word believe) (it uses trouble/persecution)
Mark 4:17 (does not use the word believe) (it uses trouble/persecution)
Luke 8:13 (uses the word believe) (aphistémi/depart)
Rom 8:35, 38-39 (nothing can separate us, even trouble/persecution)
1 Tim 4:1 ( aphistémi/depart)
Matt 13:21 But since they have no root, they last only a short time. When trouble or persecution comes because of the word, they quickly fall away.
Mark 4:17 But since they have no root, they last only a short time. When trouble or persecution comes because of the word, they quickly fall away.
Luke 8:13 Those on the rocky ground are the ones who receive the word with joy when they hear it, but they have no root. They believe for a while, but in the time of testing they fall away.
Rom 8:35, 38-39 Who shall separate us from the love of Christ? Shall trouble or hardship or persecution or famine or nakedness or danger or sword? 38For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, 39neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.
1 Tim 4:1 The Spirit clearly says that in later times some will abandon the faith and follow deceiving spirits and things taught by demons.
Luke 8:13 / Gill's Exposition of the Entire Bible - which for a while believe: their faith is a temporary one, like that of Simon Magus; which shows it is not true faith; for that is an abiding grace, Christ, who is the author, is the finisher of it, and prays for it, that it fail not. The Persic version renders it, "in the time of hearing they have faith"; and such sort of hearers there are, who, whilst they are hearing, assent to what they hear, but when they are gone, either forget it, or, falling into bad company, are prevailed upon to doubt of it, and disbelieve it. The Arabic version renders it, "they believe for a small time"; their faith do not continue long, nor their profession of it, both are soon dropped:
You seem to be applying that if one falls away from the faith due to persecution, then they were never saved because nothing would separate them from Christ, but it is the other way around. Nothing will separate Christ from us; Nothing that causes us to fall away will separate Him from us.
Your references cites why they fell away, not having roots, but Paul offers a different conclusion from what you are inferring from His words.
Colossians 2:6
As ye have therefore received Christ Jesus the Lord, so walk ye in him: 7 Rooted and built up in him, and stablished in the faith, as ye have been taught, abounding therein with thanksgiving.
8 Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ. 9 For in him dwelleth all the fulness of the Godhead bodily. 10 And ye are complete in him, which is the head of all principality and power:
All believers had received Him at the calling of the gospel when they had believed in Him, but afterwards is where discipleship comes in, and not very man continue in the word to be rooted in the faith and traditions to beware deceivers and seducers that would cause them to fall away from the faith.
Discipleship is about abiding in Him to bear fruit so that our joy may be full; it is not for obtaining salvation by. However, there is a repercussion and the call to depart from iniquity is even given out to former believers because as the church is supposed to excommunicate an unrepentant brother ( 1 Corinthians 5:4-5 ) so that they keep the commandment not to have fellowship with unrepentant believers living in sin to not even "eat" with them ( 1 Corinthians 5:11 ), then you can understand why God is judging His House first ( 1 Peter 4:7-19 ) which will happen when the Bridegroom comes, because not every saved believer will be found abiding in Him ( Luke 12:40-49 ) nor even have a desire to go because they love this life and their loved ones in it rather than leave everything behind to meet the Bridegroom in the air to join Him in Heaven for the King's Supper ( Luke 14:15-33 )
So your verses apply only to lack of discipleship for why saved believers fall away as that is the cause for them not being "fruitful".
John 15:6 If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned. 7 If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you. 8 Herein is my Father glorified, that ye bear much fruit; so shall ye be my disciples. 9 As the Father hath loved me, so have I loved you: continue ye in my love.
So there is a penalty for not running that race but we are all in that race as saved believers called to run by looking to the author & finisher of our faith in helping us to lay aside every weight & sin to be received by the Bridegroom when He comes.
Even former believers are called to depart from iniquity as 2 Timothy 2:18-21 proves and why we seek that they may depart from the iniquity of unbelief so that they may obtain that eternal glory that comes with our salvation in Christ Jesus and that is to be received as a vessel unto honor in His House. 2 Timothy 2:10-13 Any unrepentant iniquity, even religious dead works, that denies Him, they will be denied by Him ( Titus 1:15-16 & 2 Timothy 2:12 & Matthew 7:21-23 ), but even though they believe not in Him any more, He is faithful
BECAUSE He still abides as 2 Timothy 2:13 has declared that glory of God as our Saviour for all those that believe in Him, even in His name, and that is why there are vessels unto dishonor in His House.
So all believers that have received Jesus Christ are saved, regardless if they err from the truth and overthrew their faith for not being rooted in the word in walking with Him, but because He still abides in even in former believers, they are to be called to go to Him for help in discerning the lies that turned them away from Him to believe in Him again in getting ready for the Bridegroom as well as being fruitful and having their joy full in the Lord.