On the night of Pesach, we are giving testimony about Yetzias Mitzrayim. We testify about Hashem's existence based on what we actually saw and experienced. Therefore, it is important for every person to feel as if they themselves left Mitzrayim. Shabbos is also referred to as eidus, testimony, and we say that it is a remembrance to Yetzias Mitzrayim. The fact that we saw Hashem's hand directly involved in the world enables us to give testimony about Him as the Creator.