Hello FreeNChrist,
To claim OSAS, one would have to explain the following scriptures, just to name a few:
"I am the true vine, and my Father is the gardener. He cuts off every branch in me that bears no fruit, while every branch that does bear fruit he prunes so that it will be even more fruitful. You are already clean because of the word I have spoken to you. Remain in me, as I also remain in you. No branch can bear fruit by itself; it must remain in the vine. Neither can you bear fruit unless you remain in me. “I am the vine; you are the branches. If you remain in me and I in you, you will bear much fruit; apart from me you can do nothing. If you do not remain in me, you are like a branch that is thrown away and withers; such branches are picked up, thrown into the fire and burned."
In order to receive the promise of eternal life, the branches/believers must remain faithful in Christ. If not, then they cannot bear fruit and are good for nothing but to be broken off and thrown into the fire.
"Who then is the faithful and wise servant, whom the master has put in charge of the servants in his household to give them their food at the proper time? It will be good for that servant whose master finds him doing so when he returns. Truly I tell you, he will put him in charge of all his possessions. But suppose that servant is wicked and says to himself, ‘My master is staying away a long time,’ and he then begins to beat his fellow servants and to eat and drink with drunkards. The master of that servant will come on a day when he does not expect him and at an hour he is not aware of. He will cut him to pieces and assign him a place with the hypocrites, where there will be weeping and gnashing of teeth.
The scripture above is directed towards servants, for he calls the Lord, "Master." If that servant goes back to living according to the sinful nature (beating his fellow servants, eating and drinking with drunkards (partying)), then that servant will be treated as an unbeliever, a hypocrite.
My brothers, if one of you should wander from the truth and someone should bring him back, consider this: Whoever turns a sinner from the error of his way will save his soul from death and cover over a multitude of sins.
The scripture above is also directed to believer's, for the example is to those who are in Christ. Notice that if a believer wanders away from the truth, then in that state they are accumulating a multitude of sins and are on their way to death. When a believer stops having faith and goes back to living according to the sinful nature, then they have wandered away from faith.
There is no such thing as OSAS, for all of the promises through Christ require the believer to continue from faith to faith, from first to last.
