You don't have to say literally ' I deny Christ' to be an antichrist. Anyone could be an antichrist, Heck Oprah even stated that there are many ways to go to heaven than just Christ. Is that not against Christ?
This is not what Scripture says: you are adding to Scripture to come to that conclusion.
According to Scripture, an antichrist is not anyone who is "against Christ," which would be a literal meaning of the English word used for the Greek "antixristos." I find it interesting that you found the Hebrew definition of "blasphemy" (karaph) but you did not post the Greek definition for "antichrist." One might wonder why that is. Surely Strong's, your reference for the Hebrew word, also has the New Testament Greek in it. I don't have access to a Strongs right now, but I doubt the word "antichrist" is missing. You could have looked that one up just as easily.
Or maybe you did, and realized the definition was not at all what you believed an "antichrist" was, so rather than change you view to match Scripture, you decided to keep your old view and ignore what your Bible tools were telling you. Sure, Bible tools can be wrong sometimes. I always recommend someone seek the counsel of an expert in cases where you have contradictions like this, though it certainly isn't necessary to be fluent in Greek and Hebrew, or even to have access to a concordance, in order to read the Bible. But if you see something that challenges what you believe, and you hear something that seems to agree with what God is saying, and disagrees with what your initial belief was, you might want to step back and think rather than holding on to your view blindly.
The "christ" in "antichrist" does not mean that the person is opposed to Jesus. The Greek word "christos" is not Jesus' name but his title. He is "the anointed one." The Hebrew word is "Messiah."
An antichrist is not someone who is opposed to Jesus, the Christ. An antichrist is someone who
has been anointed for a specific purpose: to oppose God, and/or to oppose God's people.
John gives us only one indication of how to spot "the antichrist" -- of how to tell that someone might be anointed as The Enemy. That only clue is that they deny that Jesus is the son of God. That's it. Nothing about blasphemy. Nothing about unsound doctrine. Nothing about liberal theology. Someone who denies that Jesus is the son of God.
I have seen the videos where Obama chuckle while discussing the Bible. To me, it is pretty obvious that he is not laughing at the Bible, but rather he is laughing because it's clear, from the words in the Bible (or at least in that one passage that he quotes), that Scripture is supporting his party's platform -- at least in that one particular issue of poverty -- and is speaking against the Republican policy. The chuckle is due to what we call "irony," when we see a paradox or seeming mix-up. In this case, Republicans, who claim to have the religious moral superiority over Democrats, get some things wrong when it comes to the Bible. Not everything, mind you -- I know the Democrats get a lot of things wrong, too. But the video you're referring to, it's pretty clear what's going on, and only a fool would think that Obama was being blasphemous or disrespectful.
Be that as it may, even if he were blaspheming, that is not, as I stated before, a sign of the antichrist, one who is anointed for the specific task of opposing God.
There are plenty of potential candidates for that title. Anyone who has heard the story of Jesus, but has not converted to Christianity, could be an antichrist. That means almost all non-Christians in the world. There are a few corners in the world that have not been evangelized, where missionaries have not reached to tell the story, but for the most part, everyone has had the chance to meet Jesus, and has either accepted or denied. So, well over half of the population of the world is a potential antichrist. I don't think every person who denies Jesus is an antichrist -- I don't think they are all anointed to oppose God. But they are all potential candidates.
You know who else falls in this category? Thomas Jefferson, one of our founding fathers. He has written that he denies that Jesus was the son of God. He likes Jesus' teachings, they're all nice, but he does not accept the idea of Jesus being God. Therefore, he is a potential antichrist. In fact, many of the founding fathers held similar beliefs, and are equally solid candidates.
However, since about the mid 1800s, every American President has been pretty solidly Christian, at least publicly, if not in actuality, and to my knowledge, none of the last 30 presidents have ever made a statement denying Jesus' deity. That includes Obama.
No, Obama is not an antichrist, no matter how you slice it.