Taking the Lord's name in vain means using "God" and "Jesus" as curse words.
The Reality
It's true that you should avoid using "God" and "Jesus" as exclamatory statements when you're not actually talking about God. For my part, I try to avoid using any terms that refer to God unless I actually mean it, but I'm not personally offended when people casually say things like "Lord have mercy" etc.
But I strongly believe that the worst case of taking the Lord's name in vain is when people claim to be His followers, but then their actions demonstrate the oppposite. That is what is most offensive to God.
Another translation for the word take in Exodus 20's account of the 10 commandments is lift. We should not lift God's name in vain.
Why It Matters
God demands reverence. While what we say does matter, it fades in comparison to how we live our life. First and foremost, we must make sure that our life is not taking the Lord's name in vain. Whether by our words or by our actions, we must make sure we are truly lifting up God's name, and not dragging it down in the mud.
