I see it as we were saved when we believe, are saved and in His kingdom, and salvation will be complete at the Second coming of Christ.
Colossians is a great book to read.
note (copied from Blueletterbible.com):
[Col 1:9-17 KJV] 9 For this cause we also, since the day we heard [it], do not cease to pray for you, and to desire that ye might be filled with the knowledge of his will in all wisdom and spiritual understanding;
10 That ye might walk worthy of the Lord unto all pleasing, being fruitful in every good work, and increasing in the knowledge of God;
11 Strengthened with all might, according to his glorious power, unto all patience and longsuffering with joyfulness;
12 Giving thanks unto the Father, which hath made us meet to be partakers of the inheritance of the saints in light:
13 Who hath delivered us from the power of darkness, and hath translated [us] into the kingdom of his dear Son:
14 In whom we have redemption through his blood, [even] the forgiveness of sins:
15 Who is the image of the invisible God, the firstborn of every creature: 16 For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether [they be] thrones, or dominions, or principalities, or powers: all things were created by him, and for him:
17 And he is before all things, and by him all things consist.
Noted this:
-which hath
made us meet to be partakers of the inheritance of the saints in light
-Who
hath delivered us from the power of darkness, and
hath translated [us] into the kingdom of his dear Son:
There are other verses saying we are children of God, adopted of God, and are spiritually circumcised and complete in Him (Col. 2).
In Phillippians we read:
Phl 1:6 Being confident of this very thing, that he which hath begun a good work in you will perform
it until the day of Jesus Christ:
So we are spiritually saved, and our sanctification is progressive, and our salvation fully realized at the Second Coming (day of Jesus Christ).
I am also OSAS because of Who is the one who does the saving. He sees into our heart, and knows all and what will be. Our salvation is dependent on God's will, not our whim.