This is not the whole of Christian soteriology, nor necessarily even a part of it. But this is the problem with the common conception of Christian "salvation":
Christianity is, by definition, an exclusive religion. Anyone can become a Christian, but doing so means accepting an exclusive doctrine. According to Christ, “I am the way and the truth and the life. No one comes to the Father except through me.”There is, actually, an ecumenical movement in Christianity that is accepting of other world religions. Thomas Merton studied Buddhist teachings in Abbey Gethsemani. Pope Francis pointedly promotes dialogue with Muslims and Jews. There is, at one level, a widely disseminated sense of the unity of the human family that accepts all expressions of religion, or even non-expressions of religion, as acceptable and even honorable.
This, by definition, means other religions are “false.” It’s a bold claim; there’s no denying that.
And then there's the stupidity of people like Matt Lewis. I call his statement stupid only because he presumes to speak for me in claiming that my Christianity means I have to read John 14:6 the way he does. Granted, to even engage this argument on this verse is to accept the standard hermeneutic that Christianity is first and foremost about metaphysical salvation (preservation of the immortal soul, or saving it from damnation). So let me quote Bultmann on this passage, from his magisterial study of the Gospel of John, one heavily influenced by Kierkegaard and approaching this entire passage (it's part of the Farewell Discourse in John's Gospel. Jesus goes on and on for 5 chapters, never observing the communion initiation of the Synoptics, and, as one of my New Testament professors said, sucking all the air out of the room.).
Bultmann starts with v. 4 of chapter 14:
The wording of v. 4 is provocative; the believer was addressed on a subject he ought to have known about, and yet did not. It has the effect of drawing his attention to what has been given him, and thus of inciting him to ask a question about it. It is Thomas who does so (v. 5)--foolishly, like the Jews (7:35f,; 8.22), because he should have known long ago whither Jesus is going. His question is typical of the mythological standpoint, which can only conceive fo the goal and the way as things within the world. And yet to this extent the question has been put correctly: it makes clear that the disciple's knowledge of his own way depends on knowledge of Jesus' [going].[Bultmann uses a great deal of koine Greek freely; I will translate as best I can.]Bultmann has a way of packing a great deal into a small space. His exegesis here is not based on the standard hermeneutic that Jesus is all about saving souls, and that the Gospel of John is the locus of salvific teaching to help you escape the flames of Hell. Bultmann doesn't even start there, but it is difficult to understand what he is getting at if you don't set that hermeneutic aside as one (at least) among many. Per Bultmann's exegesis Jesus here is not declaring a soteriology, he is in fact making a Christological statement (he equates himself with God, a direct challenge to the Jews of the community the Gospel of John is written for) and a wisdom statement (very much in line with Jewish/Hebraic teachings. Rabbis, after all, are teachers; and how does one learn wisdom except by being taught?). Jesus is not, here, declaring himself as somehow the "way" to Heaven (salvation), but the way to God and wisdom and "life into the ages." That phrase is the Greek phrase used in the Synoptics more than in John, and usually translated, less helpfully, as "eternal life." It is not necessary, in other words, or I think even proper, to read the Gospel of John as a metaphysical guidebook to the afterlife (that's a very Gnostic reading, ironically. Ironically because Bultmann notes the analogy to Gnosticism in v. 6, but points out again that the Gnostic teaching relies on what he calls the "myth," which v. 6 abandons. Reading Bultmann, I would say Lewis' interpretation of John 14:6 is reinstating the myth and missing the point of the original altogether.).
Jesus' answer in v. 6 corrects the mythological thinking:
[I am the way, and I am truth, and I am life," replies Jesus. "No one gets to the Father unless it is through me.]**
By describing himself as the way Jesus makes two things clear: 1. His case is different from that of the disciples; he does not need a "way" for himself, as the disciples do, rather he is the way for them; 2. the way and the goal are not to be separated as they are in mythological thinking. In the myth the redemption has become embodied in a cosmic event, and therefore--contrary to the intention of the myth--it is conceived as an intra-mundane event, as a divine history, which takes place apart from the existence of man [sic], who is referred to it as the guarantee of his future. According to John the redemption is an event which takes place in human existence through the encounter with the Revealer, with the result that the believer's present is already based on his future; his existence is eschatological existence; his way is at the same time his goal.
Bultmann underscores this a few paragraphs on:
But the believer finds God only in him, i.e., God is not directly accessible; faith is not a mystical experience, but rather historical existence that is subject to the revelation.The "way" is not a way to salvation, any more than it is a path to wisdom ("Follow this map. 'X' marks the spot.") Jesus' declaration that he is "the way" is both a turn on Thomas' question (not really an answer, at least not to the question Thomas asked) and a statement made in the context of an early 2nd century community struggling for its identity as now (then) "Jews" (people from Judea) who have, within recent memory lost the Temple in Jerusalem and are only now beginning that rabbinic Judaism we all now think of as the religion of Judaism. Against that struggle the Christians (Jews who have converted, in John's community) assert their own identity, much as the other Gospel writers did (the Pharisees in particular are the ancestors of the rabbis). Must we also understand the anti-semitism that arose as a weed in historical Christianity is an essential feature of the religion? If we do not, why can we not reject the interpretation of John as a basis for an exclusionary Christianity?
That means that there is no "short cut" to the correct understanding of [truth] and [physical life]. The discovery of this [truth] is not something established once and for all, at men's [sic] disposal, such as could be communicated in "condensed form" like a truth of science on the contrary everyone has to take the way to it for himself [sic], for only on the way does this truth disclose itself. Similarly Jesus is the truth; he does not simply state it. One does not come to him to ask about truth; one comes to him as the truth. The truth does not exist as a doctrine which could be understood, preserved, and handed on, so that the teacher is discharged and surpassed. Rather, the position a man [sic] takes vis-a-vis the Revealer decides not whether he knows the truth, but whether he is "of the truth," that is to say whether his existence is determined by the truth, whether the truth is the ground on which his existence is based. And as in Christianity everyone has to start for himself [sic] from the beginning, so too there is no such thing as a history of Christianity which world-history, in the sense of a history of ideas or problems, in which one progresses from stage to stage, from solution to solution; each generation has the same original relation to the revelation.
If however that is the answer to the question Thomas raised, as to the way that leads to the goal which is beyond historical existence, then this much is clear: the questioner is referred back to his [sic] own historical existence.
Is it really essential to our salvation that somebody else be damned? Is it really essential to our Christianity that somebody else be wrong?
*"Thomas says to him, 'Master, we don't know where you're going. How can we possibly know the way?" John 14:5, SV. I find it very helpful not to take verses out of context in order to exegete them properly.
**The translation is from the Scholar's Version, which appends this note to the verse: "This may state the rhetoric of Jewish/Christian conflict that occasions this gospel--or one side of it--as much as the absolute claim it is usually taken to be. Perhaps Jesus here speaks mainly positively, to reassure his followers, as v. 7 shows." V. 7, by the way, reads: "If you do recognize me, you will recognize my Father also. From this moment on you know him and have seen him." You have to go quite a ways from that to "And those who don't, burn in hell!"
Quotes from Rudolf Bultmann, The Gospel of John: A Commentary, tr. G.R. Beasley-Murray, R.W.N. Hoare, and J.K. Riches. The Westminster Press, 1971.