I would like to take a minute here to attempt to explain why it distresses me when people question "OSAS." From the way I see it, to question the completeness of salvation and to think that it can be lost by a person's actions automatically has to mean that you believe it is earned by a person's actions--so, it bothers me when you question OSAS because it makes me think that you don't understand how salvation happens to begin with.
The scriptures plainly teach us that not a one of us is righteous through ANY of our doings. We end up obedient to the Word of God because of faith in the atoning death of Christ--given to us as a gift from the Grace of God that makes us alive in Christ. Then, we begin the journey toward Him, growing in Grace and knowledge of Him. We are clothed in His Righteousness, not our own. We become His Children, and He keeps us.
Bottom line: People who have been given the Grace gift of faith in Christ WILL be conformed into His image. There are dozens of verses that say that. If salvation is a work that is wholly done by a Holy Christ who became sin for us and suffered the wrath of God against our sin, our justification is full and complete IN CHRIST ALONE. Our only hope is our faith in HIS righteousness--and people who believe that are experiencing the death of their flesh and the growing life of their spirit, but it will not be complete in us until Christ returns, and we are changed or until we are resurrected with Him.
Romans 11 (ESV)
29 For the gifts and the calling of God are irrevocable.
33 Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgements and how inscrutable his ways!
34 “For who has known the mind of the Lord,
or who has been his counsellor?”
35 “Or who has given a gift to him
that he might be repaid?”
36 For from him and through him and to him are all things. To him be glory for ever. Amen.
Romans 3 (ESV)
9 What then? Are we Jews any better off? No, not at all. For we have already charged that all, both Jews and Greeks, are under sin, 10 as it is written:
“None is righteous, no, not one;
11 no one understands;
no one seeks for God.
12 All have turned aside; together they have become worthless;
no one does good,
not even one.”
13 “Their throat is an open grave;
they use their tongues to deceive.”
“The venom of asps is under their lips.”
14 “Their mouth is full of curses and bitterness.”
15 “Their feet are swift to shed blood;
16 in their paths are ruin and misery,
17 and the way of peace they have not known.”
18 “There is no fear of God before their eyes.”
19 Now we know that whatever the law says it speaks to those who are under the law, so that every mouth may be stopped, and the whole world may be held accountable to God. 20 For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin.
21 But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it— 22 the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: 23 for all have sinned and fall short of the glory of God, 24 and are justified by his grace as a gift, through the redemption that is in Christ Jesus, 25 whom God put forward as a propitiation by his blood, to be received by faith. This was to show God's righteousness, because in his divine forbearance he had passed over former sins. 26 It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus.
27 Then what becomes of our boasting? It is excluded. By what kind of law? By a law of works? No, but by the law of faith. 28 For we hold that one is justified by faith apart from works of the law. 29 Or is God the God of Jews only? Is he not the God of Gentiles also? Yes, of Gentiles also, 30 since God is one—who will justify the circumcised by faith and the uncircumcised through faith. 31 Do we then overthrow the law by this faith? By no means! On the contrary, we uphold the law.