Because that's the let down of New Year's Eve: it promises that, in a year, if you can just try really hard and stick it out, you will stop being the kind of person you are right now. But that's a lie.
The fact that I've now read through the Bible a couple of times only shows that I can force myself to do something I don't always want to do - but it doesn't change the fact that I'm the kind of person who doesn't always want to read my Bible. Which, though it seems benign, makes me a pretty audacious kind of sinner - the very words of the only God are available to me at any given moment, promising me that, by hearing from my Maker, I will have access to the things I was made for... the words of God that people in the past shed their blood to translate and print so I could read them now, the words of God that people today would take drastic measures to read if they were only literate, or allowed by their governments to do so. People face death in our world this moment for reading something I have to resolve to pick up because, let's face it, a lot of the time I just don't care about any of that stuff. That's the kind of person I am in my flesh.
The point is, as seen in my own life, the New Year might possibly be able to promise a healthier you, or a better educated you, or a nicer you, or a richer you, but if it tries to promise a new you, it cannot deliver.
But the Bible says that "if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come." (2 Corinthians 5:17) The old has passed away. The only way to be made new is to get the old gone, not just covered up or forgotten about or evolved out of.
Which is why the Gospel, not the New Year, is where we can find actual hope: when you trust in God to rescue you from yourself and your sin, the record of the kind of person you are is placed on Christ on the cross, and is killed. "For our sake, God made him who had no sin to be sin for us..." He became that wretched old person you were. And the new you? It doesn't come from resolving to be better, and to try harder, and to buckle down. It comes from the work of Christ on the cross, because he became our sin for us "...SO THAT in him we might become the righteousness of God." (2 Corinthians 5:21)
Jesus becomes the old you on the cross. And once he takes the old you and kills it, he makes you an entirely new person in its place, which is being transformed into the image of himself - righteous. sacrificial. loving. compassionate. unafraid. delightful. at peace. And isn't that better than just a better you?
I thank God that, by his grace and his work, I can honestly say that no longer who I was nearly twelve years ago when I repented of my sin for the first time and experienced a complete renewal. And I am so glad. Have you found what I have? Have you believed this amazing news for yourself yet? If not, it's a new year... why not ask our great and gracious God for a new you?