Pastor Don Esposito of the Congregation of Yahweh* in Israel gives a thorough and completely Biblical explanation of why Passover is the most important day of the year.
Passover, the first of what we know to be the annual Jewish Holy days, was ordained by Yahweh during the time of Moses. The Israelites had been in captivity, under the Egyptian pharoah and Yahweh had mercy on them made a covenant with them. They were to put the blood of a perfect lamb on the doorpost of their homes in order to be spared when the angel of death passed over and killed the first born sons of the Egyptians. This event very clearly foreshadowed the greater sacrifice that would come hundreds of years later, when Yahushua died on the cross on the very same day - Passover, bringing forth a new covenant. Those who believe in the Lord, Yahushua Messiah (aka Jesus Christ), will be saved when the next Passover comes, the one spoken of in Revelation.
Passover is the yearly renewal of a believer's covenant with Yahweh; a memorial and anniversary of the day. It is a day for us to reflect on what Yahushua did for us. It's a solemn time for self-examination (not others, but ourselves), so we are worthy to partake in the covenant. Your part in the covenant is the belief, acceptance and water baptism - surrendering your old self to Yahweh. It is receiving the Spirit of Yahweh that makes you a first-fruit. Passover Day is not a time of celebrating but a time of reflecting. The bread, the wine, the bitter herbs and the foot washing as Yahushua did with His disciples, renews our covenant. The following day the Feast of Unleavened Bread begins.
In the video, Pastor Esposito references the following verses pertaining to Passover, and it's meaning to believers today - both Jews and gentiles:
1 John 3:4
1 Corinthians 11:17-34
1 Corinthians 5:6-8
1 Corinthians 15:20-24