Am I saying that a righteous and just good will revoke His pledge?
Ephesians 1:12-14
13 In Him, you also, after listening to the message of truth, the gospel of your salvation-- having also believed, you were sealed in Him with the Holy Spirit of promise, 14 who is given as a pledge of our inheritance, with a view to the redemption of God's own possession, to the praise of His glory. NAS
What OSAS advocates totally ignore is that we are saved by grace (a gift) through
faith. We receive the Holy Spirit by faith, we are made righteous by faith, without faith it is impossible to please God. So what happens when a man falls from faith? He gives back the pledge and annuls the promise, his looses his righteousness, and he looses his salvation.
The Holy Spirit is given as a pledge of our inheritance in Jesus. What is a pledge and how and why is a pledge withdrawn or given back? God does not revoke His gifts but we by an act of our free will can give back His gifts.
Romans 1:17
17 For in it the righteousness of God is revealed from faith to faith; as it is written, "But the righteous man shall live by faith."
NAS
Galatians 3:11-14
11 Now that no one is justified by the Law before God is evident; for, " The righteous man shall live by faith. " 12 However, the Law is not of faith; on the contrary, "He who practices them shall live by them." 13 Christ redeemed us from the curse of the Law, having become a curse for us-- for it is written, "Cursed is everyone who hangs on a tree"-- 14 in order that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promise of the Spirit through faith.
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Hebrews 10:35-38
35 Therefore, do not throw away your confidence, which has a great reward. 36 For you have need of endurance, so that when you have done the will of God, you may receive what was promised.
37 For yet in a very little while,
He who is coming will come, and will not delay.
38 But My righteous one shall live by faith;
And if he shrinks back, My soul has no pleasure in him.
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Galatians 6:6-10
6 And let the one who is taught the word share all good things with him who teaches. 7 Do not be deceived, God is not mocked; for whatever a man sows, this he will also reap. 8 For the one who sows to his own flesh shall from the flesh reap corruption, but the one who sows to the Spirit shall from the Spirit reap eternal life. 9 And let us not lose heart in doing good, for in due time we shall reap if we do not grow weary. 10 So then, while we have opportunity, let us do good to all men, and especially to those who are of the household of the faith. NAS
What is the end result of loose of faith?
1 Corinthians 6:9-11
9 Or do you not know that the unrighteous shall not inherit the kingdom of God? Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals, 10 nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, shall inherit the kingdom of God. 11 And such were some of you; but you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus Christ, and in the Spirit of our God. NAS
Revelation 21:7-8
7 "He who overcomes shall inherit these things, and I will be his God and he will be My son. 8 "But for the cowardly and unbelieving and abominable and murderers and immoral persons and sorcerers and idolaters and all liars, their part will be in the lake that burns with fire and brimstone, which is the second death." NAS
The key to receiving and keeping the promises of God is by faith and faith alone.
OSAS can be disproved by what both Jesus and Paul plainly taught and they both taught that some will fall away from the faith, which save us, makes us righteous before a righteous God, and by which we receive the promise or pledge of the Holy Spirit.