"Therefore purge out the old leaven, that you may be a new lump, since you truly are unleavened. For indeed Christ, our Passover, was sacrificed for us." (1 Corinthians 5:7)
Who is the "you" to whom Paul was writing? Who is the "our", who is the "us"?
The Passover observance is for supernatural protection for the firstborn. Jesus' death saves no one.
"Therefore whoever eats this bread or drinks this cup of the Lord in an unworthy manner will be guilty of the body and blood of the Lord. But let a man examine himself and so let him eat of the bread and drink of the cup. For he who eats and drinks in an unworthy manner eats and drinks judgment to himself, not discerning the Lord’s body. For this reason many are weak and sick among you, and many sleep." (1 Corinthians 11:27-30)
Passover is observed annually after sunset on Nisan 14.