Probably Romans 8:16 is the greatest assurance text in the entire Bible. It is appealed to by Reformed and Arminian evangelicals alike, though they have conflicting ideas of assurance.
Romans 8:16 reads, “The Spirit Himself testifies with our spirit that we are God’s children.“ Arminians say this means that true Christians do have true assurance of a present, but, losable salvation. The Reformed view says that what the Holy Spirit and the Christian’s spirit testify to is a present assurance of unlosable eternal life. One of these views certainly is false and one may be true.
The text, itself, on the surface does not settle this difference. It only says that His spirit and our spirit testify to our being (at the moment) children of God. Arminian and Calvinist agree on that: the text itself only asserts a present experience. So we agree on what the text says and differ on the context and what follows from what it says.
Let us consider the Arminian view. It says that the Christian may and does have assurance of true eternal salvation, but he may lose that salvation. If the Holy Spirit testifies along with his spirit, he has eternal life only at that moment. He may, however, sin so as to lose that salvation at any future moment. The Arminian can never be sure before he dies that such fall(s) may not occur, the Arminian can never have more than momentary assurance of eternal life until he enters heaven and for the first time has assurance of eternal life. Nevertheless and alas, according to the Arminian view of “free will” he cannot have assurance of eternal life even in heaven, because as long as he has that “free will,” which he considers essential to human nature, he must be able to choose for or against God.
The question is, Can the Arminian have assurance? Obviously not on Arminian principles. Even as he believes that the Spirit is testifying with his spirit, he knows that he may, of his own tree will, reject the Holy Spirit even while the Spirit is testifying. True, he may not reject Him. But who knows? Surely, not he who must always be free to change his mind. Not even God can be sure whether the Arminian will be saved because if God knew beforehand, this Arminian would not be “free” to change his mind. If he did, God’s knowledge “beforehand” would be proven false.
Some Arminians try to keep their theology and escape this charge. They say, God’s knowing beforehand does not determine my will and thus destroy my freedom. However, it destroys the freedom the Arminian affirms because something being certain beforehand means that the man will not, and therefore cannot, choose otherwise. Thus, he cannot be free and human in his evangelical understanding of things.
The Arminian cannot have assurance for one moment though the Holy Spirit Himself is testifying at this moment that he is a child of God. This evangelical must be able to reject the Holy Spirit’s testimony at any moment.
The Arminian, therefore, cannot, on his principles, have assurance of even momentary salvation, not to mention eternal salvation.
The Arminian interpretation thus destroys the testimony of Romans 8:16. If an Arminian evangelical claims even momentary assurance of salvation, he is a living contradiction. If he is true to his evangelicalism, he cannot have assurance. If he has assurance, he is not an Arminian.
Let us now consider the Reformed understanding of Romans 8:16 and assurance. It claims the text teaches that the Christian has a testimony of the divine and human spirits to the Christian’s eternal salvation. I have shown that this is an impossibility on Arminian principles. However, it is not only compatible with Reformed principles, but grows out of them. If there were no Romans 8:16, one could deduce it from hundreds of texts.
First, “children of God” (8:16) are heirs of God and joint-heirs with Christ forever (8:17) and cannot fall because they never cease to be the children of God. Arminians deny that this is possible. There are only two historic theologies that make any serious claim to being biblical, namely the Reformed and the Arminian evangelical. I am taking these two theologies as they understand themselves regarding this one text. The Reformed view affirms perseverance of the saints and the Arminian view denies it. Arminianism has been tried and fails because its own principles make even a momentary testimony of the Holy Spirit impossible. Reformed principles, in contrast, are perfectly harmonious with a testimony of the Holy Spirit because they teach that once a person is born again, that seed never dies and so remains in essential harmony with the Holy Spirit, who begot it, and with His testimony.
To, this concurrent testimony does occur and it will never change—except for the better. Furthermore, it must be a joint testimony to eternal life, giving the regenerate soul assurance of persevering in eternal life.