That should read “and prefer to leave the manner undefined or to state that it is spiritual.”
All Christians know the Real Presence.
Transubstantiation is not Biblical and simply odd as often presented as literal.
Given the increases in understanding of chemistry and physiology it just sounds odd and goes way beyond anything the early believers would have thought or been able to consider.
What is strange is the adherence to this literal interpretation that somehow the wafer or bread, a food, becomes actual literal human flesh contrasted with rather non-literal interpretations of other Biblical passages, eg being fine with evolution or other things.
Odd double standards.
My daughter interned in a Methodist Church this past year and they took the leftover bread home and ate it.