These are the three major themes of Pesach:
Emunah/Belief
The Ramban says at the end of Parsha Bo that the miracles of Yetzias Mitzraim established three fundamental principles of belief: the existence of God, Hashgacha Pratis and Prophecy. These principles are the foundation of performing mitzvos and seeing the Godliness in everything.
Hodaah/Thankfulness
We thank Hashem for Yetzias Mitzraim, Matan Torah and making us His nation. As the Ramchal points out in Mesillas Yesharim in Zerius, we can show our thanks to Hashem by doing His mitzvos. This is why we meticulously perform the mitzvos on the seder night.
Cheirus/Freedom
Materialistic pursuits such as desire, ego-gratification, and worldly distraction imprisons our soul and prevents us from focusing on Hashem and His mitzvos. The anti-materialistic diet of Matzah powers the first stage of breaking free from the shackles of materialism.
