The only way you can establish OSAS is to ignore direct Biblical evidence that shows otherwise.
Jesus is the vine and we are the branches. No man can be a branch of Christ unless they actually believe. Who prunes the unfruitful branches off of the vine of Christ and why do those brances cease to be fruitful?
You can quote Scripture after Scripture that states only one position but it takes ignoring the others to establish a doctrine not taught in Scripture.