If ever a verse was taken out of context,...
If we suffer, we shall also reign with him: if we deny him, he also will deny us: (2 Timothy 2:12)
What does abiding have to do with performance?
I don't think the New Covenant model has angels dragging hardened backsliders into Heaven kicking and screaming, either.
What is the "OSAS issue?"
Denying and losing faith are quite different.
True believers can lose faith for a period by He will refresh them in His Love.
Denying is a different matter and the ability to renounce the Faith is taken away from the true believer, when the indwelling of the Holy spirit comes and the Spirit of the Fear of the Lord prevents us from so doing.
One must keep in mind that letters to the churches were read to wheat and tares alike so warnings about falling away were meant for the ears of those who were not really in the faith but benefitted from the fellowship with its blessings...