“Do you not know that if you yield yourself to anyone as obedient slaves, you are slaves of whom you obey, either of sin, which leads to death or of obedience, which leads to righteousness?”  (Rom 6:15-16)

Even St. Paul isn’t sure if his salvation:  “that I may know him and the power of his resurrection, and may share his sufferings, becoming like him in his death, that if possible I may attain the resurrection from the dead.  Not that I have already obtained this or am already perfect; but I press on to make it my own, because Christ Jesus has made me his own.(Phil 3: 10-11)

St. Paul says:  Well, I do not run aimlessly, I do not box as one beating the air; but I pommel my body and subdue it, lest after preaching to others I myself should be disqualified.  (1 Corinthians 9:26-27) – Paul would have known whether the early church believed in "once saved always saved" and yet he seems to be worried about his own salvation. This verse contradicts the theology of once saved always saved!

“If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such a thing as deadly sin, about which I do not say that you should pray. All wrongdoing is sin, but there is sin that is not deadly.” ( 1 Jn 5:16-17)  Shows that even though you have been saved you can still sin and that sin can lead to death. Doesn’t sound like once saved always saved!  This verse also backs up the Catholic belief of venial and mortal sins.

“He who says "I know him" but disobeys his commandments is a liar, and the truth is not in him;”  (1 John 2:4) We must believe the correct truth in order to be saved.  Truth is not subjective to our own fallible
interpretation.

“Now the works of the flesh are obvious: immorality, impurity, licentiousness, idolatry, sorcery, hatreds, rivalry, jealousy, outbursts of fury, acts of selfishness, dissensions, factions, occasions of envy, drinking bouts, orgies, and the like. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God.” (Gal 5:19-21)

“Beloved, do not imitate evil but imitate good. He who does good is of God; he who does evil has not seen God.” (1John 1:11)  Unless you’re saved?  Doesn’t say this!

“and you will be hated by all for my name's sake. But he who endures to the end will be saved.”  (Matt 10-22).  Why endure if we have been saved already?

“There is no partiality with God.” (Rom 2:11) Unless you’re saved?  Doesn’t say this!

“Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling; for God is at work in you, both to will and to work for his good pleasure.  (Phil 2:12-13)  Why work out your own salvation if you’ve been saved?

“Note then the kindness and the severity of God: severity toward those who have fallen, but God's kindness to you, provided you continue in his kindness; otherwise you too will be cut off.” (Rom 11:22)

“This charge I commit to you, Timothy, my son, in accordance with the prophetic utterances which pointed to you, that inspired by them you may wage the good warfare,  holding faith and a good conscience. By rejecting conscience, certain persons have made shipwreck of their faith, (1 Tim 1:18-19)  Shows that it is possible to fail in your faith.

“You have heard that it was said, You shall not commit adultery.  But I say to you that every one who looks at a woman lustfully has already committed adultery with her in his heart. If your right eye causes you to sin, pluck it out and throw it away; it is better that you lose one of your members than that your whole body be thrown into hell.  And if your right hand causes you to sin, cut it off and throw it away; it is better that you lose one of your members than that your whole body go into hell.”  (Matt. 5:27-30)  Sins can lead to death!

“Jesus said to his disciples: "I am the true vine, and my Father is the vine grower.  He takes away every branch in me that does not bear fruit, and every one that does he prunes so that it bears more fruit.  You are already pruned because of the word that I spoke to you.  Remain in me, as I remain in you.  Just as a branch cannot bear fruit on its own unless it remains on the vine, so neither can you unless you remain in me.  I am the vine, you are the branches.  Whoever remains in me and I in him will bear much fruit, because without me you can do nothing.  Anyone who does not remain in me will be thrown out like a branch and wither;  people will gather them and throw them into a fire and they will be burned.”  (John 15:1-8)  Jesus states that one must continually remain in him or he will be thrown into the fire.  This verse also contradicts faith alone.

“For the love of money is the root of all evils; it is through this craving that some have wandered away from the faith and pierced their hearts with many pangs.”  (1 Tim 6:10)  Shows that we can loose our faith.

“but my righteous one shall live by faith,and if he shrinks back,my soul has no pleasure in him.  But we are not of those who shrink back and are destroyed, but of those who have faith and keep their souls.” (Heb 10:38-39)

“Judge not, that you be not judged. For with the judgment you pronounce you will be judged, and the measure you give will be the measure you get.”  (Matt 7:1-2)  “Once Saved” believers do not realize it but they are actually casting judgment onto themselves by declaring themselves “saved”.  

“The Father judges no one, but has given all judgment to the Son” (John 5:22)  We cannot judge ourselves as being absolutely saved.  Christ only will judge us!