In both (as with memorialist communion) there is an unhelpful divorce between the physical act and an internal realm: where 'the action' really happens.
In sex it leads to a proliferation of fantasy sex (porn) and/or a growing uncomfortability with the physical act. The mechanics of sex put us off and we retreat into remembrances of the real thing. All the while, the pressure for sex to be "mind-blowing" makes actual love-making less and less likely.
In preaching it leads to sermons that offer the raw materials of gospel proclamation but there's no belief in the 'real presence' of Christ 'in, with and under' the preacher's words. Preaching does not hand over Christ, it merely calls truths to mind and leaves the congregation to piece it together in their own internal worlds.
Here's another area, ripe for the divorce between physical acts and the real meaning: prayer. Let me ask you some questions:
How do you feel about prayer beads? Why?
Do you close your eyes when you pray? Why?
Do you pray silently? Why?
There is an explicit reference to silent prayer in the bible. Hannah came to the temple to pray for a child:
Hannah was speaking in her heart; only her lips moved, and her voice was not heard. Therefore Eli [the Priest] took her to be a drunken woman. (1 Samuel 1:13)
The High Priest thought only a drunk would pray silently! He was wrong of course. But it's interesting what his expectations were. And it's interesting how our expectations have almost completely inverted. Prayer, for us, is a silent and utterly internal act. As with communion, as with sex, as with preaching, apparently all the action happens between our ears.
And when we do physically pray (especially with others) we find our prayers are peppered with "Just... really... Lord... hmmmm.... Just.... Just... LORD... HMMMM.... Really...." We know we're praying but we feel that... really... you know... we should... REALLY... MEAN IT! We feel that prayer is one thing but the main thing is a "spiritual" frame of mind - one which becomes increasingly difficult to muster.
Are you the same? When I pray with others I "hmm" along, as is our evangelical wont, I say 'Amen' but still I sense a lack of emotional intensity in my soul. So I attach a silent addendum to the prayer-time: "Lord, Really. I meant that one. Please. Mmm." Is it just me?
I'm tempted to think that the act of praying is one thing, but on top of that there's a pressure. A pressure to really mean my prayers. And so I leave prayer meetings with furrowed brows and sage nods and an intangible fear that I wasn't 'engaged' enough. Perhaps - Oh dear - I was just 'going through the motions.'
But I wonder whether I'm labouring under a pretty serious misapprehension. Maybe I'm imagining that my prayers themselves establish a connection between myself and the Father. Perhaps I've been duped into thinking my prayers must make the journey to the throne of grace. In which case, they'd better be good! They better be sent up with a fair bit of impetus. What kind of thrust do rockets need to escape the earth's gravitational pull? Well surely I need to match that intensity - emotionally speaking!
But what if my prayers don't travel to the throne of grace. What if Christ has already made that journey? What if I'm not shouting up to heaven. What if I'm at the Father's right hand - whispering in His ear? What if my prayers go, not in my name, but in Jesus' name? What if their efficacy is not determined by my heart towards God, but Christ's heart? What if the Spirit is Himself praying within me (Gal 4:6)? What if I genuinely have the Father's ear before and apart from any of my "prayer-righteousness"?
Then I can just pray. I can take the focus off my internal world, and simply speak to my heavenly Father. Of course, as I do that, I might just find myself "really meaning" my prayers. Great! When you understand the real presence of Christ in the Supper, you're free to commune with Him in your heart. When you understand the real connection which sex brings, you're free to commune with each other in a personal way. When you understand the real presence of Christ in the sermon, you're free to receive Him powerfully in your pew. But it's got to start with the reality.
Prayer really connects with God - not because you really connect with God but because Christ does. Prayer really works, but it works apart from any of your fickle feelings. So, speak to your Father and rest your confidence, not on your own heart, but on Christ's.
So the High Priest shall bear the names of the sons of Israel in the breastpiece of judgment on his heart, when he goes into the Holy Place, to bring them to regular remembrance before the LORD. (Exodus 28:29)