It is unpopular outside of Christian circles to mention Jesus' claims, "I am the light of the world," or "I am the way, I am the truth, I am the life. No one comes to the Father except through me." Such statements are quickly criticized, accused of a false exclusivism. Those who believe Jesus (aka Christians) of course contest the "false" part, but have not always got around to the next phase of the conversation: that Christ is not "exclusive" in the sense typically meant.
Jesus' Meta-Religious Claims
Consider, for a moment, Buddhists seeking enlightenment, or Taoists seeking the Way, or philosophers seeking truth. Noble, lofty goals all of them, and good quests. It is a bedrock-level misunderstanding to imagine that Jesus disparages these quests. "I am the light" shows Christ as the source of light behind that "enlightenment" which the Buddhists seek. "I am the way" shows Christ as that way which the Taoists seek. "I am the truth," he says to those who look for it. This hardly scratches the surface, but already we need to stop and look at the subject of syncretism (with all the good and bad that lurk behind that approach). After that, we'll return to Jesus' meta-religious claims.
Can Syncretism Solve the Problem?
Syncretism, the mixing and/or blending of religious beliefs, has a long and distinguished history filled with both good and bad. First the good side. Syncretism tends to acknowledge the common streams which flow through all of those religions which tend towards good: love, mercy, truth, strength, courage, humility, self-control, peace, patience, kindness, gentleness, and more. Syncretism acknowledges that there is, after all, one truth. Has anything ever been truer than that ultimate truth must belong to all people on earth simply because of the nature of reality? Ultimate good must belong to all people on earth for the same reason. Syncretism acknowledges these things. Syncretism also tends to avoid partisanship, or the silly notion that we must deny the existence of mere decency in other religions.
On the other hand, syncretism has not always had what you would call rigorous standards of truth, honesty, or even justice to the views being discussed. Important distinctions are frequently swept under the rug. Genuine differences are either welded together awkwardly or lopped off entirely with a weak pretense that, if it did not fit, it must not have really mattered. Syncretism does not always deal fairly with the very beliefs that are supposedly "cherished" under its inclusive wings. It threatens a homogenized religion which may be either an unrecognizable hybrid of the strong features of different religions, or a watered-down well-wishers' club if the strong features are eliminated. The watered-down version is inoffensive of course, but "inoffensive" is not exactly high praise. It is difficult to see how anyone could seek truth or gain love from its pursuit. It is more difficult still to see why anyone would want to follow in the first place. It becomes debatable whether enough remains to merit the name "religion" because, as much as detractors of "organized" religion denounce the organization, it is the organization of coherent beliefs on the subject that cause it to be called by the name "religion". After syncretism, what is left is often compared to a buffet in which people can take the candy of any system they choose, avoid the bread and butter, and come out ill-fed, not having experienced any religion at all adequately, but self-congratulatory and appearing very ecumenical all the same.
Syncretism seeks to preserve what is good from all sources, but it tends toward the insistence that all is good everywhere. This leads to logical inconsistencies to say the least. The way out of syncretism is to acknowledge that some things actually don't work together, and take the hard road to acknowledging differences, seeing which things are actually closer to the truth, which things are actually better. When necessary -- and it does become necessary -- the hard road includes figuring out and acknowledging when things are false or harmful, wrong or evil.
Is the Alternative Enmity?
I've already mentioned that it becomes necessary to take the hard road, actually figuring out and acknowledging when things are false, harmful, wrong, or evil. But just as syncretism can be overdone, so can faultfinding. If the focus becomes seeking out whatever is false and wrong, whatever is harmful or evil, the harm goes beyond just bringing out the worst in ourselves and in our hapless targets. We lose sight of the desire for God or for goodness which springs up in each religion; we find ourselves attacking what should have been our starting point. Once the starting point is demolished, we find we have neither common ground nor good will with which to rebuild, and besides have left integrity behind by attacking that in which there was good. In extreme cases, it seems as if the goal becomes to justify one's own beliefs by faultfinding someone else's with the intent of locating evil; when it goes to that extent, then good reason has been left behind.
What is worshipped as Unknown
When the apostle Paul spoke to pagan idol-worshippers, he could have taken Isaiah's path when Isaiah strongly jibed at his fellow Hebrews for falling into idolatry. But the Hebrews had known better; Paul's listeners had not. The ancient Greeks' religion was about as false as it comes, and had a good share of harmful aspects if Paul had sought to say so. But he was not so much interested in attacking their beliefs as in announcing Christ. Paul brought good news. It was not a game to score points at the expense of opponents, it was a chance to see people born again into a living hope by the resurrection of Christ. And so Paul, facing idol-worshippers, began with gentleness and respect: "I see that you are in every way very religious. For as I walked around and looked carefully at your objects of worship, I even found an altar with this inscription: TO AN UNKNOWN GOD. Now what you worship as something unknown I am going to proclaim to you." (Acts 17:22-23)
When it comes to other faiths, have we walked around and looked carefully at their objects of worship? If not, then we have not done our homework, have not followed Paul's example, and have no right to expect the same kind of reception of the message.
Does Jesus Transcend Religion?
In the sense that Jesus is Ultimate Truth, he transcends religion. In the sense that Christianity is following Jesus Christ, it also transcends religion. If you have ever listened to the nickel-and-dime internet skeptics, the less educated will trot out endless claims of how Christianity "borrowed" from every other religion on the planet. The timelines and comparisons don't really work out to plagiary, but the discussion should not end there. It really is not a stretch to notice Christ fulfilling the hopes of other religions. I've sketched out in some detail how Christ fulfilled the Messianic expectations of Judaism. We'll take a quick overview of how Christ fulfills the expectations of some other religions as well.
There are some religions like Taoism where I am not inclined to name anything particularly "false" about it. I would explain Christ to a Taoist very simply: he is that ancient path which you seek, the goodness beyond mere morality. He is that self-existent way. Read what he said, see for yourself. "Follow me," he says. (I might also give them a copy of: Christ, The Eternal Tao, an Eastern Orthodox view of the Tao Te Ching as a preparation for Christ.)
Likewise, to a Buddhist, I would invite simply: You are looking for "enlightenment" but do you know how to get there or how to explain it or how to achieve it? Do you understand what the light is? Christ is the light of the world; if you want enlightenment, listen to him and he will tell you what it is and how to get there. (If he were in a joking mood and familiar with Western culture, I'd suggest that Buddhists sometimes fake enlightenment like Charismatics sometimes fake speaking in tongues, and for much the same reasons.) I might also mention that "right thought, right action, right purpose" and so forth of Buddhism are ill-defined in practice, and Christ can explain those: Love the Lord your God with all your heart, mind, soul, and strength, and love your neighbor as yourself. Christ would never ask someone to turn away from the right path; he claims to be that right path.
To a Hindu I would say: You want to be reincarnated to be "born again" and purify yourself. But what is made new with physical rebirth is only the body; reincarnation of the body would do no good. It is the Spirit that must be born again. Flesh gives birth to flesh and Spirit gives birth to Spirit; you must be born of the Spirit of God. And I'd make sure they started with the Gospel of John, then show them the Sermon on the Mount which Gandhi praised so highly.
Now, again, there's something about brevity that's nearly as bad as syncretism: I can't possibly do justice to someone else's beliefs in roughly 100 words or less. I doubt I could do my own beliefs full justice in that space. These are simply conversation-starters that have grown from my own efforts to "walk around and look carefully at the objects of worship" before proclaiming Christ. I don't claim that these are the best conversation-starters possible; maybe your own explorations will give you better than these. But I am certain that this is good ground to explore.
Is Christ Exclusive?
In the sense that Ultimate Truth is for everyone, and the Creator of all things is necessarily Lord of all, Christ is all-inclusive. Every glimmer of truth and goodness in other religions points back to Christ. We say this because Christ is the eternal, unchanging one that all are seeking. In the sense that Christ is the only one for the whole world, and the only one who can save from death: yes, that is exclusive. But we are carelessly antagonistic or lazy if we do not study the hopes of mankind, especially as organized into world religions, and do better than "you are wrong" which is not entirely right; the truth we proclaim is "Christ fulfills your hopes."