In John 4 Jesus tells the Samaritan woman at the well that he has the Water of Life, and if she drinks of it she will never thirst again. (I always found it odd that it took her so long to get that this was a metaphor since He just asked her for a drink of water.) Later, in the same account, He tells His disciples that He already has food – which is to do the will of His Father.
In John 6 we see Jesus use a few loaves of bread and a couple fish to feed thousands. The next day they’re hungry again. He uses this opportunity to try to teach them a spiritual parallel: “Eat my flesh and drink my blood.” OMG!
I never used to get this. It was scandalous! How could that possibly have a parallel meaning?
Here, Jesus is laying down a seriously heavy metaphor! Partaking of His flesh and blood is simply partaking in what He is doing/will do – by faith. His work is to do the will of the Father; Our work is to believe in the one doing the work. Period. By believing in Him and that He fulfilled the work of the Father, we are doing our part and have been granted (not earning) eternal life.
We don’t have to physically do ANYTHING. It is already bought and paid for! (John 19:30 – “It is finished” actually means “It is paid in full”)
If we come to Him, if we believe in Him, we will never hunger, never thirst.
Now, keep in mind, John 3:36 says that if we truly believe in Him, we WILL obey Him. By doing what we calls us to do, by following Him, we are satisfied, refreshed (Psalm 23). We don’t do what He asks of us to “earn” anything, we simply have the joy and peace that comes with knowing that we are participating with (partaking of) Jesus’ work.
So, what exactly is Jesus’ flesh and His blood? Personally, I believe His “flesh” was what He was physically doing (teaching, healing, etc) and His blood was what He was going to do spiritually (through His crucifixion and resurrection).