But first, please allow me to give some helpful background behind the "all in" claim: When God established the Passover it accomplished at least two things: 1) it was a time of remembering and celebrating God's great "exodus" of His People. In other words, God's people were celebrating God's promise to rescue them, freeing them from slavery as He moved to ultimately fulfill His promise to Abraham (that all peoples on Earth may be blessed through him - Ge. 12:3). 2) It is the full understanding of THAT entire story and all it means that also always pointed forward, to the time when His people would be celebrating the One True Sacrificial Passover Lamb, who we remember & celebrate each time we participate in the Lord's Supper.
God sent Jesus at just the right time for the ultimate "exodus" of His people. In Jesus, He rescues His people once and for all, freeing them from the slavery of a life of sin. In other words, He frees His people from the grip of the Evil One, dealing a final and lasting blow to the satan's attempts to wreak havoc as he prowls around looking for prey to devour. (1 Ptr. 5:8)
In Jesus, God has overcome, victory is His. Jesus has taken His rightful place and offers Hope, Rescue, Saving and Freedom. And God is fulfilling His promise to Abraham that all peoples on Earth (from every tribe, tongue and nation) may be blessed through him.
And so, as we fast forward to today, we see a People who celebrate, remember and participate in the greatest Passover event. God remembered His promise to Abraham and fulfills it in Jesus. God invites the whole community of Israel (His people), whose hearts have been circumcised, who've been washed by the blood of the Sacrifical Lamb, who have been brought through the Red Sea in Jesus' death and resurrection, coming out the other side to a new beginning, a new life which claims allegiance to this King who has come to their saving rescue, freeing them from the slavery of sin and all its horrific consequences of brokenness, decay, destruction and even death as He makes all things new.
So now, let me say, that THIS celebration, this glorious participation in this commemorative event (referred to by many names) known here as the Lord's Supper, is an "all in" event. God says it's for all who stake their lives on what God has done in the Person of Jesus. He says, the "ALL IN" people, those who take up their cross and follow Him, THEY are His people, they are ones He has established this meal for:
"God said to Moses & Aaron, '...No foreigners are to eat it. Any slave, if he's paid for & circumcised, can eat it. No casual visitor or hired hand can eat it...The whole community of Israel is to be included in the meal.'"(Ex. 12:43-47 The Message)
He gave all of Himself for us, of course He would ask the same in return. :)