"For if He were on earth, He should not be a priest, seeing there are priests that offer gifts according to the law." (Hebrews 8:4)
Back up a bit to the psalms and see what the psalmist had to say regarding the outward working of inward devotion:
"I will not reprove thee for thy sacrifices or thy burnt offerings, to have been continually before me. Offer unto God thanksgiving; and pay thy vows unto the most High. And call upon me in the day of trouble: I will deliver thee, and thou shalt glorify me." (Psalm 50:8, 14-15)
It would seem the psalmist got an inside angle on what God is really like. Panentheism is where "God" is resident in all things. One conclusion you'll draw if you follow this theology is that all things are sacrosanct as all things fall under the category of "God". God is everywhere. Okay. This doesn't sound too different from a simple explanation of who the Holy Spirit is. But you (or I) don't just get to see the Holy Spirit without putting forth some effort in His direction. The Holy Spirit is invisible but He is indeed all around us. Continuing the passage begun at the top of the page:
"Who serve unto the example and shadow of heavenly things, as Moses was admonished of God when he was about to make the tabernacle: for, See, saith He, that thou make all things according to the pattern shewed thee in the mount." (Hebrews 8:5, emphasis mine)
The author of Hebrews is seeking to point out that Christ lived in His body, all of the various and sundry symbolisms the Law of Moses created. There, in His flesh and blood, is the outworking of a heavenly pattern. And Jesus was not seen as the Christ by everyone while He walked this earth. God (in Christ) will show up where you least expect Him. This is because of an inherent strain of unbelief. He revealed Himself to Moses in a burning bush. He walked alongside two disciples making their way from Jerusalem to Emmaus and they didn't know it was Him. One of the things God likes to do to His people is surprise them. Sure, it helps to be on the lookout to begin with, but the finer-tuned your perceptions may be, the more unique the visitation. Consider this:
"Clouds and darkness are round about Him..." (Psalm 97:2a)
What do you think of when you read this? Obscurity. That's what it brings to mind. Shadows. Just because God shows up in ways we least expect—even in ways that may seem scary and terrifying while they're happening—doesn't mean it's not Him. Thing is though, if you know the Lord, He certainly will surprise you but you'll also have peace about the encounter. When once you think you've wrapped your mind around God, He'll be sure and upset your (already outmoded) notions. But how does all this refer to idolatry? Here's how: No physical object you come into contact with is going to do you any good if you don't know the Lord already. With Jesus's death and resurrection, the physical has taken a back seat to the spiritual. But now that the Lord has risen and reigns, physical objects are again holy. Though not in a way that makes them venerable and worthy of worship.