Easter is the holday when the Christian world commemorates the resurrection of Jesus Christ. Why is the life and resurrection of Christ important? When I try and understand the importance if something I try to imagine life without it. What would life be like without Christ?
Philosophers and sociologists have tried to define exactly what makes humans different from animals. In another sense, we could ask, what causes humans to act differently from animals? Why do some humans act in selfless, self-sacrificing ways to strangers, turn-the-other-check, and forgive? I believe it is because of the light of Christ and our faith in Jesus Christ.
God, who is the creator of the universe, lives. However, God's existence wouldn't necessarily impact human behavior if we didn't know about His existence and nature. God, being God, could greatly control our lives regardless of our knowledge of Him. But that's not how God works. God has revealed that He is not about controlling our lives. Instead, God "leaks" information about Himself and His will, so that only those who are seeking Him will find Him.
For those that have found God, our Heavenly Father has revealed to us by His Son Jesus Christ commandments. It is through these commandments that we learn that "the natural man is an enemy to God" and it is God's will that man act with restraint. If it wasn't for this revealed knowledge, there would be no reason for humankind to not just be controlled by our fears and appetites. Without God, it would be "dog-eat-dog". God's commandments make us free by giving us a choice. We can be hungry but choose to fast; offended, but choose to forgive.
If it wasn't for Christ's atonement and resurrection, humankind would have no hope for redemption. So many decisions we make in life are based on fear and scarcity. We fear death, and we fear not having enough. These fears cause us to hoard resources, and take what we can get now instead of sacrifice the good we have now for better later.
All humankind are imperfect, sinful, and mortal. But because of Christ, we have a hope that we can repent, improve, and one day be resurrected and become citizens of a perfected society. Without Easter, the hearts of man would become hopeless and depressed, and resign ourselves to just "eat, drink, and be merry; for tomorrow we die". But because of Jesus Christ's power over sin and death, His disciples can enjoy a perfect brightness of hope.