There are a number of things about the Christian faith which are often taken for granted by those who hold to it when we speak of it. But misunderstandings, or lack of formal definitions, are common. So this article is part of a brief series in which the core concepts and persons will be addressed, defined, and hopefully understood in a way that allows further study.
What is Christianity?
Briefly defined, Christianity is the gospel and the life that is being changed by it. There's quite a lot there, and this series will largely be an attempt to unpack it. For today, though, it will be enough to focus on the two parts of this definition.
The gospel is a biblical concept. That is, to study it, we must look to the Bible. Now, the Bible describes the gospel from a number of angles, and as has been claimed in another series, it is ultimately present underlying the entire Bible. We could look a number of places for a definition to use here, not least in Romans (especially chapter 8); we could focus entirely on Paul's summary that "Christ came into the world to save sinners," we could examine Jesus' discussion with Nicodemus in John 3 where Jesus explains some of the basic ideas, or a host of other places. But for the sake of getting as much explained with as few words as possible, it's hard to beat 1 Corinthians 15.
Now I would remind you, brothers, of the gospel I preached to you, which you received, in which you stand, and by which you are being saved, if you hold fast to the word I preached to you--unless you believed in vain. For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures, and that he appeared to Cephas, then to the twelve. Then he appeared to more than five hundred brothers at one time, most of whom are still alive, though some have fallen asleep. Then he appeared to James, then to all the apostles. Last of all, as to one untimely born, he appeared also to me.
1 Corinthians 15:1-8 (ESV)
D. A. Carson has a rather solid treatment of this passage that can be heard here, which is worth a listen. And continuing on in reading that chapter will present a fair bit of explanation as well. But the basics are all here, so we will touch on them quickly, and then each will be addressed in more detail in later articles (and through links to previous articles where this has been touched on). The gospel is about Jesus Christ and His work. He died for our sins, but death could not hold Him, because He rose again. This is not being claimed as a conceptual idea but as a historic fact, complete with time frames and witnesses who, at the time of Paul's writing, were largely still alive and available for questioning. It is by this that we stand and are being saved, not by our own efforts or will. And all of this was done in line with scripture, which at the time largely consisted of the Old Testament.
A Life Being Changed by the Gospel
So what does it look like to have a life being changed by the gospel? It means to trust in Christ rather than ourselves. It means to seek after Christ and to place the gospel "of first importance," before anything else, including ourselves. It is a life of worship, seeking to bring glory to God through our private lives, public lives, and active outreach. It means a life being gradually changed to be more and more in line with God's nature and will. This doesn't mean that everything is perfect from day one. One of the greatest misconceptions about Christianity is that it's all about being good or that when we slip up we're somehow not 'good Christians'. But this is a focus on us, rather than on Christ, and is mistaken in that.
These are the basic ideas, and they open up a whole new set of questions which will be addressed as the series continues. If you have any specific aspects of this you would like to make sure get covered in the series, please suggest it in the comments.