Use of the word "Christian" is almost a misnomer these days. Just as anyone can claim to be a male, or a female, or both, so too can anyone claim to be a "Christian." But perhaps surprisingly to most of you, Jesus never told us to "make Christians" or anything of the sort. In fact, the word "Christian(s)" is only mentioned three times in the entire Bible. (Acts 11:26, 26:28; 1 Peter 4:16; that's it.) And when it is mentioned, the only definition given is that of a disciple -- or student -- of Jesus Christ: "And there is Antioch [in Syria], the disciples were first called Christians." (Acts 11:26)
And so you see, discipleship is what Jesus commanded -- not taking His name in vain, which is actually expressly prohibited by the 10 Commandments. We are called to lay down our lives, pick up our crosses, and give all that we have to follow Christ. We are called to live sacrificially, worshiping and honoring Him, spreading the "Good News" of the Gospel and the Cross, and avoiding sin to the greatest extent possible in our life (and confessing and repenting from those sins when we do sin). That's what the Bible calls us to -- lives fully devoted to Jesus Christ, not simply following a "code of Christian ethics" or only following a selected portion of Scripture (e.g., the Sermon on the Mount, or the Beatitudes) that makes us feel good about ourselves. To do either of those latter things apart from faith in Christ and His Cross, is actually to create a man-made works-based religion, as an attempt to justify ourselves before a holy and righteous God.
But you see, salvation -- and justification -- are by faith in Christ, and by faith alone. (Galatians 3:24) There is nothing we can do to earn our salvation or our justification, not even "living out the Sermon on the Mount" or "practicing the Beatitudes," and certainly not simply taking the Lord's name in vain.
No, you see, we are most certainly not commanded to simply call ourselves "Christians." We are commanded to be disciples of Jesus Christ, fully devoted to Him, and leaving the cares and pleasures of this world behind to serve Him with all that we have, and all that we are, because that is how He loved us first.
"For I did not shrink from declaring to you the whole counsel of God." (Acts 20:27)