In my days as a pulpit rabbi, I remember speaking about אמת and שלום as an appropriate Rosh Hashana message. As the years passed, I see just how important this message is.
The basic idea here is that one cannot achieve Shalom, which I would loosely translate as peace of mind, without Emet, facing up to the truth.
Many people choose to live with אשליות, or delusions. In many ways, this is a survival mechanism, because the truth or reality is much too painful.
The real Teshuva process is one where the individual has the courage to accept and face head on his own world. It means being prepared to admit one's mistakes previously made, and to be able to forgive oneself for those indiscretions. It also means being able to love those dear to him, despite the shortcomings these people might have. And even more importantly, the pursuit of truth might make it necessary to distance oneself from those that might have a detrimental effect on one's life.
All of this is not easy and it often comes with short term pain. But the long term gains are enormous. An individual will achieve שלום, real peace of mind. He knows what is true and what is false. He knows what to attach himself to, and what to stay away from. In short, his quest for truth will bear fruit. He will be protected from what might hurt him and he will be able to face the world with optimism and excitement.
After all, how could one go wrong when אמת and שלום are descriptions of Hashem Himself!