First, I just want to say that for a lie to be acceptable, there must be enough truth in it to make it believable. It's the untrue part that makes it a lie.
Now, let's look at Karma vs. Christianity. Why am I doing this? Because there seems to be more and more people talking about the bad things happening in their lives being associated with Karma - when there's really no link at all to certain events - except their own guilty consciences for something they've done. So they take the bad, blame it on something they've done, and hocus-pocus, their penalty is paid. How nice! No God to answer for, no eternal penalty to pay, or need for salvation. Karma makes it all just part of the "circle of life." Yet, Christianity teaches something far more satisfying, far more true, and, frankly, far more reasonable. It teaches that Jesus came to pay our penalty for sin (by dying on the Cross). That's because the penalty of sin is death: eternal separation from God in Hell. The grace of God is that He sees our need and offers the only true solution: Salvation through Jesus Christ.
Karma is ANTI-CHRISTIAN, denying the truth, leading people to ignore the truth, and so helping people reject the truth. I'm not even going into the history of "Karma" at this point. I'm simply trying to alert Christians to reject "Karma" claims and follow Proverbs 3:5-6 "Trust the Lord with all your heart, and lean not on your own understanding; In all your ways acknowledge Him and He shall direct your paths." (NKJV) Let's do that and teach our kids to do so as well.