The Incarnation is when God the Son became man, and so became the God-Man, fully God and fully Man in two distinct natures but one person.
So, why did God the Son become incarnate?
Well, here are 4 easy to remember reasons:
- Revelation - The incarnate Christ reveals the Father to us (John 1:18; 14:9)
- Salvation - Only a sinless man could pay for sinful men (Heb 2:14-17); Only God could bear the full weight of an infinite punishment.
- Destruction - To save sinners, sin had to be dealt with. 1 John 3:8 tells us that Christ came to 'destroy the works of the devil' (i.e. sin). So Christ became incarnate in order to defeat and destroy sin.
- Motivation - Although it's not the only reason He came, or even the most important, the Bible is clear that Christ incarnate is an example for believers to follow. You won't be saved by following Christ's example, but for those who have been saved, what better example could there be than the only sinless person ever to have lived? (1 Pet 2:21; 1 John 2:6).
Now, clearly that's just a brief summary and not a comprehensive statement of the doctrine, but hopefully it will help you remember.
Why did the Word become flesh? Revelation, Salvation, Destruction & Motivation.