Luke 22:17-20, Matthew 10:32-33, Matthew 16:25, Mark 3:35, Romans 6:3-5, Matthew 11:6
On the night of the Last Supper, Jesus symbolically lifted the wine and bread in a toast, and said to His disciples, “Take this, and divide it among yourselves:  For I say unto you, I will not drink of the fruit of the vine, until the kingdom of God shall come.  …This is my body which is given for you: this do in remembrance of me.  …This cup is the new testament in my blood, which is shed for you.” (Luke 22:17-20)
He didn’t set a prerequisite. Although the disciples had trained under Him, He didn’t say, ‘Now that you’ve studied under me…’ He didn’t say, ‘Being that you belong to a Church…’
The word “whosoever” is written in the Gospel accounts countless times, most often used by Jesus directly in His speech. Many times, our Lord used “whosoever” to describe those who would be saved, or those who in rejecting His salvation would be damned. Either in what they said, or how they acted.
In Matthew 10:32-33: “Whosoever therefore shall confess me before men, him will I confess also before my Father which is in heaven.  But whosoever shall deny me before men, him will I also deny before my Father which is in heaven.”
And in Matthew 16:25: “For whosoever will save his life shall lose it: and whosoever will lose his life for my sake shall find it.”
In Mark 3:35: “For whosoever shall do the will of God, the same is my brother, and my sister, and mother.”
Each time, the”prerequisite” is only to BELIEVE and confess Jesus Christ as your Lord and Savior. No tribunal to ‘grade’ your readiness. No association of Man to ‘prove’ your worthiness.
From the evidences of the Scriptures, water baptism is also not a prerequisite to accept communion with Christ. The disciples were not water baptized. And even in some of their works, it’s not clear that any water was used to baptize new followers of Christ.
In Romans 6:3-5, Paul plainly describes a new aspect of ‘baptism’ under grace. That we are actually baptized in Christ’s death and resurrection: “Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death?  Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.  For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection”
All this is to teach you: Let no man and no arcane procedure of man stand between you and Your faith and redemption in Christ. Not even the procedure of water baptism. I’m not against the procedure, for those who personally hold the ceremony as something that will signify their change from the old sinful self, to the new creature in Christ.
But know this: No droplet of water, or designation of a minister, can save you where your faith cannot. You either believe that Jesus Christ was the Lord personified, come back for you to redeem you as a pure sacrifice for all your sins, or you don’t. You either solemnly accept the gift of redemption and pledge to turn from your sins, or you go through the motions and continue living life as always you had. You are either changed into a new creature in Christ, or you are the same old one.
But BELIEF only is the prerequisite. Not a status of “communion” by a monolithic Church denomination, nor by any other earthly association. I’ve seen some strange things in my time. I’ve personally experienced the types of aforementioned false “prerequisites” floated by supposed ministers of God. True communion (that is, the symbolic remembrance of Christ’s Last Supper) and true salvation is for whosoever will.
Listen to what Jesus said. “And blessed is he, whosoever shall not be offended in me.” (Matthew 11:6) On this most special weekend, be not ashamed of your faith in our Lord Jesus Christ, but broadly share His love and His peace amongst all you know, that the lost might be redeemed through the baptism of faith. In Jesus’ name, amen.