why passover is celebrated

Exodus 12:1-28
The Passover Instituted

3 Speak to all the congregation of Israel, saying: ‘On the tenth of this month every man shall take for himself a lamb, according to the house of his father, a lamb for a household.

6 Now you shall keep it until the fourteenth day of the same month. Then the whole assembly of the congregation of Israel shall kill it at twilight. 7 And they shall take some of the blood and put iton the two doorposts and on the lintel of the houses 
14 ‘So this day shall be to you a memorial; and you shall keep it as a feast to the Lord throughout your generations. You shall keep it as a feast by an everlasting ordinance. 
18 In the first month, on the fourteenth day of the month at evening, you shall eat unleavened bread, until the twenty-first day of the month at evening.
24 And you shall observe this thing as an ordinance for you and your sons forever.
25 It will come to pass when you come to the land which the Lord will give you, just as He promised, that you shall keep this service. 26 And it shall be, when your children say to you, ‘What do you mean by this service?’ 27 that you shall say, ‘It is the Passover sacrifice of the Lord, who passed over the houses of the children of Israel in Egypt when He struck the Egyptians and delivered our households.’” So the people bowed their heads and worshiped.

Matthew 26:17-19
Jesus Celebrates Passover with His Disciples

17 Now on the first day of the Feast of Unleavened Bread the disciples came to Jesus, saying to Him, “Where do You want us to prepare for You to eat the Passover?” 18 And He said, “Go into the city to a certain man, and say to him, ‘The Teacher says, “My time is at hand; I will keep the Passover at your house with My disciples.”’” 19 So the disciples did as Jesus had directed them; and they prepared the Passover.

Not only does the Word say to keep Passover but Jesus kept the Passover.  Jesus is ou