Worshipping before wood or stone would not in itself be idolatrous. What would be idolatrous is the belief that there was either no objective referent which existed independently of that wood or stone, or, alternatively, that the supposedly objective referent had a nature very dissimilar to that of the actually existing God.
I take exception to this aguement of intent and I point you to the Book of Exodus, chapter 32:
1 When the people became aware of Moses’ delay in coming down from the mountain, they gathered around Aaron and said to him, “Come, make us a god who will be our leader; as for the man Moses who brought us out of the land of Egypt, we do not know what has happened to him.”
2 Aaron replied, “Have your wives and sons and daughters take off the golden earrings they are wearing, and bring them to me.”
3 So all the people took off their earrings and brought them to Aaron,
4 who accepted their offering, and fashioning this gold with a graving tool, made a molten calf.
Then they cried out, "This is your God, O Israel, who brought you out of the land of Egypt."
5 On seeing this, Aaron built an altar before the calf and proclaimed, “Tomorrow is a feast of the LORD.”
6 Early the next day the people offered holocausts and brought peace offerings. Then they sat down to eat and drink, and rose up to revel.
7 With that, the LORD said to Moses, "Go down at once to your people, whom you brought out of the land of Egypt, for they have become depraved.
8 They have soon turned aside from the way I pointed out to them, making for themselves a molten calf and worshiping it, sacrificing to it and crying out, ‘This is your God, O Israel, who brought you out of the land of Egypt!’
9 I see how stiff-necked this people is," continued the LORD to Moses.
10 “Let me alone, then, that my wrath may blaze up against them to consume them. Then I will make of you a great nation.”
The Israelites called the molten calf “the Lord who brought you from the land of Egypt.” For this act God would have destroyed them all if not for the intercession of Moses.
It is clear from this and the rest of the OT that the act of worshipping some “thing”-wood or stone-regardless of the intent is idolatry.
What makes the Eucharist different is that it was not instituted by any human being but by Christ. The bread and wine are not changed by anyone else’s power but God’s.
St. John Chrysostom:
“It is not man that causes the things offered to become the Body and Blood of Christ, but he who was crucified for us, Christ himself. The priest, in the role of Christ, pronounces these words, but their power and grace are God’s. This is my body, he says. This word transforms the things offered.”
And St. Ambrose of Milan:
“Be convinced that this is not what nature has formed, but what the blessing has consecrated. The power of the blessing prevails over that of nature, because by the blessing nature itself is changed. . . .
Could not Christ’s word, which can make from nothing what did not exist, change existing things into what they were not before? It is no less a feat to give things their original nature than to change their nature.”
The Eucharist, along with the cross, are stumbling blocks. It forces us-like those men in that synagouge in Capernaum-to make that choice that causes us to forget what we see with our eyes and accept His words with faith; **“This IS My Body…This IS the cup of My Blood.” **
I the Church’s teaching on the real presence:
The mode of Christ’s presence under the Eucharistic species is unique. It raises the Eucharist above all the sacraments as “the perfection of the spiritual life and the end to which all the sacraments tend.” In the most blessed sacrament of the Eucharist “the body and blood, together with the soul and divinity, of our Lord Jesus Christ and, therefore, the whole Christ is truly, really, and substantially contained.” “This presence is called ‘real’ - by which is not intended to exclude the other types of presence as if they could not be ‘real’ too, but because it is presence in the fullest sense: that is to say, it is a substantial presence by which Christ, God and man, makes himself wholly and entirely present.”
It cannot be idolatry, because through Him, with Him, and in Him we give to God the Father what He gave, and continues to give, to us in the Spirit: His Son. And in consuming the Body and Blood of our Lord Jesus we become sanctified by Him, and thus are offered in turn by Him and with Him as members of His Body to the Father. This is the fulfillment of the OT worship, a worship “in spirit and truth”, and the “pure offering” that the Prophet Malichi foretold of.
Does the bread taste like flesh? No. Does the wine taste like blood? No. Is it suppose to? No. Do we believe it is really our Lord? Yes. Why?
Because He said so.