A go-to passage for evidence from Jesus that Christians can lose their salvation is John 15:5-6. Jesus says,
I am the vine, you are the branches. He who abides in me, and I in him, he it is that bears much fruit, for apart from me you can do nothing. If a man does not abide in me, he is cast forth as a branch and withers; and the branches are gathered, thrown into the fire, and burned.
Obviously, that a branch can be cut off from the vine implies that it once was a part of the vine, living with the life of the vine. And when it’s cast forth, it dies.
Just as branches live with the life of the vine when united to it, so too Christians live with the life of Jesus when united to him. And just as branches can be separated from the vine and die, so too Christians can be separated from Jesus and die spiritually, since to be separated from Jesus is not to have salvation. Therefore, Jesus teaches that Christians can lose their salvation.
There aren’t many comebacks Protestants make to a Catholic’s appeal to John 15:5-6. John Calvin argued that Jesus speaks of those who merely appeared to be Christians but were not in reality [1]. Since this reading is so contrary to the plain sense of the text (Jesus says, “he who abides in me,” not “he who appears to abide in me”), most Protestants don’t use it.
(It’s interesting that the only other place where Jesus speaks of abiding in him is with reference to the Eucharist: “He who eats my flesh and drinks my blood abides in me, and I in him” [John 6:56]. The Eucharist is key to remaining on the vine and not being burned.)
There is one comeback, however, that some Protestants use: “Jesus is not talking about eternal punishment. Rather, he’s talking about temporal punishment.”
Robert Wilkin counters by targeting the Catholic assumption that Jesus is talking about eternal judgment. He argues that Jesus is speaking about temporal judgment. Wilkin supports his claim by appealing to what Jesus doesn’t say. He writes,
Since the Lord did not use the verb to be burned up, but rather the less intense verb to be burned, he is holding open the possibility that the unproductive believer may respond to the burning and return to fruitfulness (450).
For Wilkin, the image of the branch burning up would have to be present if Jesus intended his teaching to mean that a Christian can be definitively separated from Jesus and receive eternal damnation. Since Jesus doesn’t use that image, but rather simply says the branch will burn, Wilkin concludes that Jesus isn’t talking about eternal judgment.
How can a Catholic answer this Protestant comeback? Well, one glaring problem with this argument is that it doesn’t fit with the viticultural imagery.
As Catholic Bible scholar Michael Barber argues, “Why would a vinedresser cut off and ‘burn’ a branch in order to restore it?” Burning a branch doesn’t restore the branch; it destroys it.
A second problem is that the language “burned” doesn’t suggest something temporary. The same language jibes just as easily with the view that Jesus is talking about the Final Judgment and the everlasting burning that someone separated from Jesus will experience. That person will be forever “burned.” Given this ambiguity, anyone using the “burned but not burned up” argument would have to provide further evidence to defend his claim that this is a temporary burning. Until he does, this counter-argument is an assertion without evidence.
Finally, consider the Greek. First, there’s nothing there to suggest that this is a temporary burning. Second, there’s only one other time in the New Testament where the Greek word translated as “burned” (kaiō) is used, and that’s Matthew 13:40. It’s used in relation to judgment, and it’s used for the Final Judgment, which implies an everlasting burning: “Just as the weeds are gathered and burned [Greek, kaietai] with fire, so will it be at the close of the age. The Son of Man will send his angels, and they will gather out of his kingdom all causes of sin and all evildoers, and throw them into the furnace of fire, where there will be weeping and gnashing of teeth.”
[1] See John Calvin, The Gospel according to St. John: Part Two, 11-21 and the First Epistle of John, trans. T.H.L. Parker (Grand Rapids, MI: Eerdmans, 1959), in loc.; cf. Michael P. Barber, “Response to Robert N. Wilkin,” in Four Views on the Role of Works at the Final Judgment, 68.