Phil: I believe all religions contain truth, and therefore any religion followed well is good.
Jim: I believe salvation can be found through Christ alone.
Phil: Isn't it just great that we believe things?!
Jim:... err.. I, uh,
Phil: Well, I gotta get back to work!
A friend of mine had a conversation very similar to this. When words like belief and truth have been taken from their original Christian meanings we are often at a loss when trying to communicate the truth of the gospel. How can Phil believe "A" and Jim, "not-A" and everything be hunky-dory? Yet, so often we come across people who don't understand that belief and truth is not something soft you can put on like a sweater, but rather it is a rock that you will either build upon or be crushed against.
A Quick Primer on Truth
The Medievals said that truth was the extent to which a description matched its objective reality. So, when I say that I am typing on a black laptop, anyone who could see me now would see that this description matches the objective reality of my body actually sitting and typing on the black laptop. This is true. If I said I was typing on a purple laptop there is no way in which we could make this mesh with the physical reality. This would be untrue.
No one, not even Phil, would disagree with the above paragraph. They can hold on to this description of truth and yet simultaneously hold that anything personal does not require a physical reality. Restated: 'The laptop is black' and 'the buddha is good' are believed by many to be two different kinds of truth. The first one requires a corresponding physical reality and the second does not. In fact, the second statement only requires a feeling or an internal disposition to validate it.
Christianity requires a corresponding objective reality to all truth-claims.
To prove this rather outrageous claim (according the the world at large) I will cite the following passages: Gen. 1, and John 1:1-5.
Genesis states that creation was spoken into existense. God spoke "let there be light." and there was. John says that there was the pre-existent Word of God that created all things. This Word is then shown to be Jesus. Later, Jesus says that those that have seen him have seen the Father, and again he is the Truth. Not that he speaks truthfully, although he does, but he is the embodiement of truth.
Our definition of truth is God. Our definition of Beauty is God. Our definition of Perfect is God. All of these abstracts that the post-modern likes to base in his or her own subjective opinion (those "truths" that lack an objective reality) are intended to be placed in the objective person and character of God.
When we speak of belief and truth we need to ensure that we define our terms. I find it is easier to do this with an actual text of scripture sitting there on the table. When your coworker says "all roads lead to heaven," you can point him to the passage where Jesus says "I am the way, the truth, and the life. No man comes to the father but by me." Unlike sharing your "beliefs," which is so typical of the squishy share-athon that is our modern public discourse, texts are difficult to push around.
So live your day in the light of the objective truth of Jesus Christ. Remember you are not free to base your reality in your subjective personally experience. Our reality, our truth rests in the objective person of Jesus and his disclosure of the Father.