As a Buddhist you’re puzzled, you say, by the Orthodox doctrine of theosis. How can something that was formerly created now become increatus et increabile? Either it was so from the beginning, or it was not. And how can a man become omniscient, omnipresent, and omnipotent? If he does, he is more—you object—than even the Buddha ever claimed to be.
We’re up against paradoxes here, to be sure. But it’s a mistake to think that the Western traditions are alone in presenting such puzzles. One could very easily object to the Buddha: “What do you mean there’s a Noble Eight-Fold Path? The word ‘path’ implies that there’s somewhere to go and someone to do the going. But neither is true—or not at least if your later, Mahayanic disciples were right.”
In every tradition an appeal is made to someone, or something, that is and yet isn’t what it should be. No appeal would be possible if we weren’t already what we have to become, and no appeal would be necessary if we were already all that we are. In Christianity the “soul”, which is said to be in need of salvation, is the name for what occupies the spectrum between the is and is-not. It’s not what we’re saved from, namely, the “flesh”; neither is it what we’re saved in, namely, the “Spirit”. But it’s the place where the appeal can be effectively heard and acted on.
By the way, a deified man is in fact omniscient, omnipresent, and omnipotent. But qua “deified”, not qua “man”. Another paradox.