It is self-evident that to affirm tashbih in the sense you have just defined is something no rational person who understands his own words would ever say; sound reason knows intuitively that such a thing is impossible. Yet rejecting this absolute identity does not oblige us to deny every form of resemblance in certain respects, as happens with shared names and univocal attributes.
However, some people first choose a particular meaning and declare that this is what tashbih means; having done so, they label everyone who affirms that meaning a mushabbih (an anthropomorphist). Their opponents reply that the meaning in question does not, in fact, constitute tashbih at all.
[One of the Muʿtazilite objections: affirming the attributes entails a plurality of eternals]
Others distinguish between the terms tashbih (likening) and tamthil (representation). The Muʿtazila and other deniers of the attributes maintain that anyone who affirms an eternal attribute for Allah is both a mushabbih and a mumaththil. Thus, if someone says that Allah possesses eternal knowledge or eternal power, they brand him a mushabbih and a mumaththil, because eternity (qidam) is, in their view, the most distinctive characteristic of the Deity. Consequently, whoever affirms an eternal attribute for Allah has, in their estimation, posited an eternal peer alongside Him, and for that reason they call him a mumaththil.