Sam Harris has this to say about the Eucharist:
Of course, Catholics have done some very strenuous and unconvincing theology in this area, in an effort to make sense of how they can really eat the body of Jesus, not mere crackers enrobed in metaphor, and really drink his blood without, in fact, being a cult of crazy cannibals. Suffice it to say, however, that a world view in which “propitiatory sacrifices on behalf of the living and the dead” figure prominently is rather difficult to defend in the year 2007. But this has not stopped otherwise intelligent and well-intentioned people from defending it.
To some extent - if we are to look at reality from purely materialist viewpoint - you'd have to say he was spot on. What the Church believes occurs at the consecration is no small absurdity. And no matter how well the arguments are phrased to support transubstantiation they can't be expected to "convince" anyone that the Eucharist is true. What we are asked to accept and believe defies our senses and can only be embraced through the gift of faith. Atheists like Harris are only being honest when they make declarations like the one above.
Recently, when I've been in front of the Blessed Sacrament in our local adoration chapel, the absurdity of the experience has become very present for me. Here is this inanimate round white disc, encased in an ornate gold monstrance - and here am I, a living, breathing man on my knees worshipping it as my God!
Scientific investigation doesn't bring me there.
Logical reasoning doesn't bring me there.
Rational philosophical structures don't bring me there.
None of those things are incompatible with my Catholic faith. In fact they owe much of their current evolutionary development to the Christianity's far-reaching quest to know the face of God. However, they cannot be - and are not - the foundation for my personal, physical worship of something so visually insignificant. It is not ironic that the host is placed in expensive and ornate monstrances as much as it is a cultural and psychological attempt to give something a degree of worldly glory that our faith says it deserves, but our senses find disturbingly absent.
No arguments can ever convince anyone that this "source and summit" of our faith is in fact the Lord. But, when God gives you the grace to believe (even just a little!) the scriptures open up, Tradition opens up, and the world opens up for the light of God to pour upon it and lead you to a means of understanding that transcends the ultimate dead end of human reason. Here, in the Eucharist, is the King of Kings, and Lord of Lords - in a form more humble and less assuming of those titles then when he was a slick, red-stained infant amid the smells of livestock and manure. In the Eucharist, Christ is even more vulnerable to abuse and disrespect than when he was presented to the chief priests on Good Friday. And in the Eucharist, Christ gives mercy and life in an even more personal way than when he surrendered it from the cross.
Humanity's alpha and omega are present in the Eucharist, but we cannot, through our own devices, concoct a grand-unification theory to quantify this reality. As Christ told Peter after his outburst of faith in Matthew 16, "Blessed are you, Simon Bar-Jona! For flesh and blood has not revealed this to you, but my Father who is in heaven. "
But those who pretend to be on the solid ground of rational, materialist reality are really just avoiding the inevitable consequences of looking down. Our universe - our experience of space and forward-moving time is the by-product of our fragile consciousness. Our lives and thoughts occur in a vast absurd abyss. It is where we turn when this cold truth becomes real to us that matters.
Neils Bohr once said "Everything we call real is made of things that cannot be regarded as real. " This is an accurate description of the universe Sam Harris bases his philosophy on. The Eucharist is the only thing in the universe about which that statement can be reversed. It is more real than the "reality" in which it resides.