Ok I finally see where you are coming from. It took a while what with the verse selection. Your verse selection is great
IF
You were arguing pro-Calvin. But you are arguing pro-OSAS. Here is an example of why I misunderstood you-
1 Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; 2 By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. 3 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; 4 And that he was buried, and that he rose again the third day according to the scriptures:
That is your I Cor. 15 passage. Your very first one has an 'IF' clause in verse 2.
My question is-
Why are you using a passage that contains an 'if' clause since the clause terminates the surety?
The "if" is an "unless ye have believed in vain". A person who has believed in vain has never believed all of the elements of the gospel of Christ declared in 1 Corinthians 15:1-4 KJV.
Scripture shows us the best example of believing in vain as "some" at Corinth did not believe in "the resurrection of the dead". One who doesn't believe in the resurrection of the dead would not believe that Christ was risen. Their faith was also vain!
1 Corinthians 15:12 Now if Christ be preached that he rose from the dead, how say some among you that there is no resurrection of the dead?
1 Corinthians 15:13 But if there be no resurrection of the dead, then is Christ not risen:
1 Corinthians 15:14 And if Christ be not risen, then is our preaching vain, and your faith is also vain.
1 Corinthians 15:15 Yea, and we are found false witnesses of God; because we have testified of God that he raised up Christ: whom he raised not up, if so be that the dead rise not.
1 Corinthians 15:16 For if the dead rise not, then is not Christ raised:
1 Corinthians 15:17 And if Christ be not raised, your faith is vain; ye are yet in your sins.
Those who trust the Lord believing all of the elements of the gospel of Christ declared by Paul "are saved"! There's is no IF attached to those who "are saved"! The IF is attached to those who were never saved, but those who "believed in vain" having never trusting the Lord believing the gospel Paul declared. Understand?