If so, then he predestined everyone to be conformed to his image.
If that is the case, then everyone will be saved.
Or does foreknowledge in that context mean something other than knowing that someday they would exist?
Well, maybe you could comment on the statement of Charles Spurgeon.
You must, most of you, be acquainted with the general method in which our older Calvinistic friends deal with this text. "All men," say they, - "that is, some men": as if the Holy Ghost could not have said "some men" if he had meant some men. "All men," say they; "that is, some of all sorts of men": as if the Lord could not have said "all sorts of men" if he had meant that. The Holy Ghost by the apostle has written "all men," and unquestionably he means all men. I know how to get rid of the force of the "alls" according to that critical method which some time ago was very current, but I do not see how it can be applied here with due regard to truth. I was reading just now the exposition of a very able doctor who explains the text so as to explain it away; he applies grammatical gunpowder to it, and explodes it by way of expounding it. I thought when I read his exposition that it would have been a very capital comment upon the text if it had read, "Who will not have all men to be saved, nor come to a knowledge of the truth." Had such been the inspired language every remark of the learned doctor would have been exactly in keeping, but as it happens to say, "who will have all men to be saved," his observations are more than a little out of place. My love of consistency with my own doctrinal views is not great enough to allow me knowingly to alter a single text of Scripture. I have great respect for orthodoxy, but my reverence for inspiration is far greater. I would sooner a hundred times over appear to be inconsistent with myself than be inconsistent with the Word of God. I never thought it to be any very great crime to seem to be inconsistent with myself, for whom am I that I should everlastingly be consistent? But I do think it a great crime to be so inconsistent with the Word of God that I should want to lop away a bough or even a twig from so much as a single tree of the forest of Scripture. God forbid that I should cut or shape, even in the least degree, any divine expression. So runs the text, and so we must read it, "God our Savior; who will have all men to be saved, and to come unto the knowledge of the truth." (Metropolitan Tabernacle Pulpit, Vol. 26, Pilgrim Publications, p.50.)