If OSAS means that a person becomes a son or daughter of God permanently, then I agree with the doctrine. But if OSAS means that a person cannot be sent to the lake of fire after they have accepted Christ's atonement for them, then the Scriptures disagree.

First, there is the obvious scripture of Hebrews 6. The pertinent passage reads "For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, and have tasted the goodness of the word of God and the powers of the age to come, and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt." Why, one could ask, would this disturbing passage even be in the Bible if it were impossible for it to happen? I think I must be misunderstanding OSAS...

Revelation also has something to say on this topic, as Jesus himself immediately says, after discussing overcomers, the water of life, and making all things new, that the "cowardly, the faithless, the detestable, as for murderers, the sexually immoral, sorcerers, idolaters, and all liars their portion will be in the lake that burns with fire and sulfur, which is the second death." Why, after already covering those who aren't written the Book of Life and moving on to those who will inherit the promises, would Jesus then revisit the lake of fire with specific sins unless He meant to warn Christians that those who do such activities will be cast into the eternal fire?

And then there's Nehemiah 4:2...

I'm maintaining that a son or daughter of God can be cast into the lake of fire, but will be withdrawn after their sin is accounted for and ultimately placed into the New Jerusalem, albeit with severe dis-figuration and burns. But I don't consider that being saved, so I disagree with OSAS.