Right. And if He changed the nature of the bread, it wouldn't be bread anymore.
So is God capable of changing a substance, without changing the properties of the original substance? Or is He not able to?
Given the nature of creation, no. This falls into the same category as asking whether God can make a rock large enough that He cannot lift it, or know the color of the number 9. The assertion is logically absurd.
The substance of a thing is found it its properties, in its molecular makeup. If God changed the molecular makeup, it would become something else.
Except for that one time.
John 6:50-51
"But here is the bread that comes down from heaven, which anyone may eat and not die. I am the living bread that came down from heaven. Whoever eats this bread will live forever. This bread is my flesh, which I will give for the life of the world."
Jesus didn't start pulling pieces of flesh from his body and giving it to them right then, did he?
Or even given them any bread?
You're assuming (blindly) that "This bread is my flesh" is being spoken in a literal way, and assuming (blindly) that this happens via the Eucharist. Eucharist isn't mentioned anywhere in John 6. Nowhere do John or Jesus tie this speech to Eucharist.
Not all things that exist, exist in a physical way.
And anything that exists, exists by God's will.
Excellent. Then if the bread does not become the body of Christ in a physical way, then it isn't Christ's body.
All things, but God, exist contingently - rather than necessarily.
Only God exists, necessarily.
Existence is part of His nature.
It is not within the nature of a human being, or a stone, or a drop of water, to necessarily exist - meaning it is possible for any one of those things to not exist.
Their existence is contingent upon God's will.
As are their properties.
Fire burns things. This is one of its properties. But fire will lose this property, if God so wills it. (Daniel 3:25)
Actually, fire is the result of certain kinds of combustion. The properties of fire do not include burning things. Burning is a chemical process to which fire may contribute heat.
You see, modern science has shown that previous views of the world (such as all things comprising earth, wind, fire, and water) to be inaccurate.
A solid piece of iron does not float. Bouyancy is not one of its properties. But the substance of iron bares the property of bouyancy, if God so wills it. (2 Kings 6:5-6)
Buoyancy isn't a property. Buoyancy tells us about the density of a solid object when immersed in a liquid object, and subjected to gravity. It is a comparative term, not a term of property. If we found a liquid that was more dense than iron, iron would float on it.
Again, modern science has displaced much of ancient science in this respect.
Likewise, blood does not bare the properties of wine, nor flesh the properties of bread. But if God wills it to be so, it is so.
First, your examples fail the idea of "property." Nowhere in Scripture does the text tell us that the "properties" of anything changed. The miracles you cite are more easily explained by God's intervention (shielding in the fire, raising the ax head to the surface), than claiming that God decided to alter the nature of the universe.
Second, your examples are specific miracles that the bible identifies as miracles. Nowhere is Eucharist named as a miracle each time it occurs.
Third, in order to bear the properties of blood, it must display those properties. In order to bear the properties of flesh, it must display those properties. Flesh is not flesh without DNA. If it does not have DNA, it isn't flesh. The bread does not have DNA, thus it is not flesh.
And He does will it to be so. John 6:55
Again, you're making assumptions from the text that aren't supported in it.