“For what great nation is there that has a god so close at hand as is the Lord our God whenever we call upon Him?” (Devarim 4:7). Tur (581:4) elaborates on this verse:
What nation is like this one, which knows the character (i.e., the ways and judgments) of its God? The way of the world is that a person facing judgment wears black, wraps himself in black, and lets his beard and nails grow, because he does not know what the outcome will be. But Israel do not do this. They wear white, wrap themselves in white, shave their beards, cut their nails, eat and drink, and rejoice on Rosh Ha-shana, because they are confident that God will perform a miracle for them.
At first glance, we can ask: How can we be so confident that God will perform a miracle for us and that we will be vindicated? We see with our own eyes that many people die every year, and many others get hurt or fall ill. Clearly, they experienced no miracles.
Rather, anyone who properly observes the mitzvot of the holiday, accepts the yoke of God’s kingship, and is moved to improve their service of God can be confident of a favorable judgment, because God wants to benefit his creations. The simplest understanding of this is that God will bless us with a good year, as usually happens. But we also know that sometimes, because of a sin’s gravity or the world’s imperfection, God sees that it is best for a person to suffer or die, so that the person refines and corrects his deeds, thus earning true life in the next world. Even though we would like God’s goodness to reveal itself to us in this world without suffering, we have yet to deserve this. Nevertheless, we know that the judgment is for our own good, and we should celebrate it (Shlah, Masekhet Rosh Ha-shana, Torah Or §17).
Since God wished the Jews to accrue merit, He established the day of remembrance and shofar blasts as a day of rest and sanctity. A day of sanctity is one on which we abstain from weekday work and worries and manifest the holiness of the day through Torah, prayer, and rejoicing in the mitzva with festive meals. Had we not been commanded to celebrate Rosh Ha-shana, we would likely spend the whole day making personal requests, dreading judgment. This would not help our case. On the contrary, it would harm us, for sin happens when people forget their sacred mission and focus on personal issues. Instead, the sanctity of the day is a vehicle for the Jewish people to manifest God’s kingship in the world. This inspires them to repent out of love, meriting a favorable judgment and a blessed new year.