I had to look that one up. I think it's a GREAT metaphor for what is being said. King Sisyphus was punished in the underworld by being compelled to roll a gigantic boulder up a hill, only to watch helplessly while it rolled back down, and then to repeat this throughout eternity. A Sisyphean task is then a pointless or interminable activity.
How better to describe this rite that is performed millions of times every day in the world to millions of people? Numbering in the billions or trillions by now. People trying to have their sins expiated only to have to return and participate in the same ritual again and again throughout their lives - and this is only if they are to be considered "faithful".
How much more true to Scripture is the belief that the Lord's Supper is a commemoration and remembrance of what Jesus did for us and to remind ourselves of our own bodies that we offer as living sacrifices to God to serve him and each other in love and truth?
the only reason that we can offer ourselves as living sacrifices to God, is we first must be in Christ and united with Him in His Body, the Church. If we are in rebellion to the Body of Christ, God will reject your “living sacrifice”.