If I'm ever asked whether I'm offended by hearing the f-word, I reply that I am more offended by hearing the G-word, the J-word and the C-word.
If we go back to the Ten Commandments, then it is quite crystal clear:
You shall not take the Name of the LORD your God in vain, for the LORD will not hold him guiltless who takes His Name in vain. (Exodus 20:7)
But this is more than just using God, or Jesus, or Christ as swear words. In Ephesus there is the incident involving the sons of Sceva:
Then some of the itinerant Jewish exorcists undertook to invoke the Name of the Lord Jesus over those who had evil spirits, saying, “I adjure you by the Jesus whom Paul proclaims.” Seven sons of a Jewish high priest named Sceva were doing this. But the evil spirit answered them, “Jesus I know, and Paul I recognise, but who are you?” And the man in whom was the evil spirit leaped on them, mastered all of them and overpowered them, so that they fled out of that house naked and wounded. And this became known to all the residents of Ephesus, both Jews and Greeks. And fear fell upon them all, and the Name of the Lord Jesus was extolled. Also many of those who were now believers came, confessing and divulging their practices. And a number of those who had practiced magic arts brought their books together and burned them in the sight of all. And they counted the value of them and found it came to fifty thousand pieces of silver. So the word of the Lord continued to increase and prevail mightily. (Acts 19:13-19)
For the sons of Sceva, invoking the name of Jesus was just another magic spell. No doubt if they had been further east, they would have been invoking Kali, Vishnu and Shiva as well.
When churches baptise, they use the Trinitarian format that Jesus commanded:
And Jesus came and said to them, “All authority in heaven and on earth has been given to Me. Go therefore and make disciples of all nations, baptising them in the Name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.” (Matt. 28:18-20).
Is Jesus giving them a set of commands? Do this, make sure you also do that, and, oh, while you're at it, don't forget...?
Or is He giving them something inter-related? That baptising in His Name is more than just mentioning Him above the waters of baptism, but involves, among other things, choosing to live a life following His teachings, and the assurance of His presence with us.
In the Bible, names are important. Jesus means "The LORD saves". Christ means "The Anointed One". Abram becomes Abraham. Jacob becomes Israel. Saul becomes Paul. They signify something about the person. This isn't true in the modern world (after all, my name is an anagram of "Right Paranoid Charmer").
Taking the Lord's Name in vain is more than just going "Oh. My. God." It is ignoring His character. It is living as if He isn't there.
Sometimes a non-Christian will say "Oh my God" or "Jesus Christ!" in a response to something we have done that dishonours God. Who has taken the Lord's Name in vain there? They at least have the excuse of not knowing.