Now that this is in the Eagle's Nest, I'll chime in once here, then hang up and listen.
Alot of people believe as you do. As a matter of fact, I'm sure if you press alot of Americans, they would come to this same conclusion... even ones who profess to be Christian/Muslim/Buddhist/any other religion.
The truth is, if you dig into any of the texts (Bible/Koran/Pali Canon/etc...), or inquire with a minister for each religion, you'll find this ideology to be out of the question: A purely man-made, secular idea. And, there are plenty of secular places of worship out there as well.
Jesus professes to be God incarnate. There aren't many others who also profess this. Muhammad does not, Buddha does not. None of the major religions have this caveat other than Christianity. To use the age-old term: Jesus is either a Lord, Liar, or Lunatic. That is a question for everyone to answer on their own.
A Christian's job (Mat. 28:19) is to share the Gospel with everyone. This is offensive to many people. Hence, either the Christian backs down and does not follow through on this command and is praised as tolerant by secular society, OR that Christian acts on this command and is disliked by secular society as being offensive/intolerant.
Now, don't get me wrong, there are MANY Christians who do this in a way that is overly offensive (i.e: the dude who preached fire-brimstone in the free speach area on campus when I was there '00 - '05), and there are "Christians" who are just flat-out, NOT CHRISTIAN. (i.e: Westboro Baptist Church, Robert Tilton, this is a long list...)
Tim Tebow is doing a fantastic job of following through on his command (He's not a fantastic QB though, and the option-style offense will definitely be exposed if they make it to the playoffs, IMHO). I agree with Kurt Warner's quote above, and I think St. Francis said it beter: "Share the Gospel always. Use words when necessary." Actions speak louder than words, correct? So as long as Tebow is not living a life contrary to what he's saying, then I think he's doing as Christ instructed him.
Now, as far as the whole planking/owling/Tebowing thing? I never got into that. Am I old? Oh no! But, if you whippersnappers are having fun doing it, then by all means...