This will not be by prooftexting: It is too simplistic to prooftext your way in order to demonstrate the doctrine of eternal security of the believer, because the Arminian can cite verses per contra that he believes contradicts them when they take them out of context and don't understand what salvation is--we must take this debate to a new level and dimension: Salvation is the restoration of our relationship with God into His family as His children by adoption, whereby we are born again spiritually after being dead and alive in the Spirit to have fellowship with Him, and the Holy Spirit is given us as a down payment of our salvation and the intention of God to be the Ultimate Promise Keeper who never reneges on a promise, and to keep His Word that He will make good on what He began and finish making us in the image of Christ. (Eternal security, it is argued is not a biblical term, but the words "eternal salvation" and "eternal redemption" are in. Heb. 5:9; 9:12.)
But note this: eternal life begins in the here and now, and it is not something that is future or pie in the sky--it begins forthwith! We have (present tense!) eternal life (per John 6:37)! Eternal means that it is eternal and not provisionally based, or on a probationary status. It begins at salvation and continues on throughout eternity. Our salvation began in eternity past, is realized in time, and is consummated in eternity future.
If you understand what salvation is you will never misconstrue this doctrine. Romans 8:29-30 is called the golden chain of redemption and shows that God loses none whom He calls to justify (save) and to ultimately glorify. "And those whom he predestined he also called, and those whom he called he also justified, and those whom he justified he also glorified." Those whom He calls (the inward call), not whom we call (the general call), get justified or saved! All who are saved get glorified--none get "unjustified" there is no such a term in the Bible--none get lost in the shuffle!
Seeing the biblical metaphorical language, no one is "un-born, un-adopted, un-justified, un-found, un-sealed, un-anointed, un-quickened from the dead, eyes un-opened," or what have you. We are either sheep or goats! No one in the Bible loses their salvation! (Judas was a devil from the beginning and never did believe.) [God was] "...thus securing an eternal redemption" (cf. Heb. 9:12) for us, and this is something to see as a "done deal." Fait accompli. There's nothing we can add to or subtract from God's work: "It is finished." It is His masterpiece! The debt He paid that He didn't owe for us who couldn't pay the debt we owed is PAID IN FULL!
Now, if you realized that salvation is a gift, you will realize that you cannot earn it (it is grace all the way). And if it is a gift you didn't earn it, don't deserve it, and cannot pay it back, and you don't ever have to give a gift back, do you? In a works religion, you never know how much is enough or how little is too little--you can never be sure. Exactly what sin will ensure the loss of salvation if it is possible? No one can say for sure! The beautiful thing about our salvation is that "Salvation is of the Lord" (it is not of us and God, or of us alone) according to Jonah 2:9. That means it is not a joint or cooperative venture (synergistic) with God or one of our own works, but a gift completely is done by God (monergistic) by grace (that's the only way it could be by grace)--He just wants you to accept it freely as a right (cf. John 1:12).
Finally, if there is no eternal security, there can be no assurance of salvation, because the person puts himself under the power of his own efforts rather than God's power to redeem and keep us as our Keeper (cf. Jude 1:1). If you deny this doctrine, you must also deny the assurance of salvation and see it as mere presumption as Roman Catholics do. These doctrines go hand-in-hand and can be distinguished but not separated--they must go together like faith and works (faith without works is dead) and these two must be connected. In plain language they are the flip side of each other--you cannot have one without the other logically. Soli Deo Gloria!
But note this: eternal life begins in the here and now, and it is not something that is future or pie in the sky--it begins forthwith! We have (present tense!) eternal life (per John 6:37)! Eternal means that it is eternal and not provisionally based, or on a probationary status. It begins at salvation and continues on throughout eternity. Our salvation began in eternity past, is realized in time, and is consummated in eternity future.
If you understand what salvation is you will never misconstrue this doctrine. Romans 8:29-30 is called the golden chain of redemption and shows that God loses none whom He calls to justify (save) and to ultimately glorify. "And those whom he predestined he also called, and those whom he called he also justified, and those whom he justified he also glorified." Those whom He calls (the inward call), not whom we call (the general call), get justified or saved! All who are saved get glorified--none get "unjustified" there is no such a term in the Bible--none get lost in the shuffle!
Seeing the biblical metaphorical language, no one is "un-born, un-adopted, un-justified, un-found, un-sealed, un-anointed, un-quickened from the dead, eyes un-opened," or what have you. We are either sheep or goats! No one in the Bible loses their salvation! (Judas was a devil from the beginning and never did believe.) [God was] "...thus securing an eternal redemption" (cf. Heb. 9:12) for us, and this is something to see as a "done deal." Fait accompli. There's nothing we can add to or subtract from God's work: "It is finished." It is His masterpiece! The debt He paid that He didn't owe for us who couldn't pay the debt we owed is PAID IN FULL!
Now, if you realized that salvation is a gift, you will realize that you cannot earn it (it is grace all the way). And if it is a gift you didn't earn it, don't deserve it, and cannot pay it back, and you don't ever have to give a gift back, do you? In a works religion, you never know how much is enough or how little is too little--you can never be sure. Exactly what sin will ensure the loss of salvation if it is possible? No one can say for sure! The beautiful thing about our salvation is that "Salvation is of the Lord" (it is not of us and God, or of us alone) according to Jonah 2:9. That means it is not a joint or cooperative venture (synergistic) with God or one of our own works, but a gift completely is done by God (monergistic) by grace (that's the only way it could be by grace)--He just wants you to accept it freely as a right (cf. John 1:12).
Finally, if there is no eternal security, there can be no assurance of salvation, because the person puts himself under the power of his own efforts rather than God's power to redeem and keep us as our Keeper (cf. Jude 1:1). If you deny this doctrine, you must also deny the assurance of salvation and see it as mere presumption as Roman Catholics do. These doctrines go hand-in-hand and can be distinguished but not separated--they must go together like faith and works (faith without works is dead) and these two must be connected. In plain language they are the flip side of each other--you cannot have one without the other logically. Soli Deo Gloria!