This is probably the most employed logical fallacy of the Calvinistic believer when engaging in a debate over the claims of their TULIP systematic. Here is how the conversation typically goes:
Calvin: God brings about every meticulous detail for His own glory, including man’s sinful inclinations and choices.
Hobbs: That claim undermines the character, holiness and goodness of God who abhors moral evil (Prov. 6:16-19; Jer. 7:31), is holy or separate from all evil (Is. 6:3; Ex. 15:11) and who does not even tempt men to sin (Jm. 1:13). He is the redeemer of sinful choices, not the one who brings them about!
Calvin: YOU TOO have the same problem because you believe God knows every evil thing that is going to happen but did not prevent it.
Notice that the non-Calvinist (Hobbs) is critiquing an ACTUAL CLAIM of the Calvinistic systematic. The Calvinist does not answer that critique, but instead they commit the “you too” fallacy by appealing NOT to an ACTUAL CLAIM of the non-Calvinistic scholars, but to their own philosophical conclusion about the infinite attribute of divine omniscience – a philosophical conclusion non-Calvinists deny. So, the non-Calvinist is critiquing an actual claim of Calvinism while the Calvinist is appealing to something we deny (i.e. if God knows something and does not prevent it then it is the same as Him determining it).
Let’s take a look at this same fallacy in a “real world” discussion and see how it plays itself out:
Calvin: I hired a mean kid at my son’s school to bully him so as to toughen him up so he can represent my name in a strong powerful way.
Hobbs: You did what?!? How can a good and loving father do that to his own child?! If your son finds out what you did he will never trust you again.
Calvin: YOU TOO did the same thing last year when your son told you about that bully and you sent him to school anyway. You didn’t have to send your son to school knowing there was a bully there. You could have prevented him from being bullied, but you didn’t, so YOU TOO are as bad as I am!
Hobbs: WHAT!? I did not hire some mean kid to mercilessly torture my son. I hated that he went through that. I wept with him. I worked with him every night on what to say and do in order to confront his bully. I helped redeem that horrible situation to make him stronger. I did not cause it, or bring it about, or make it happen for my own namesake. If someone went to my house and convinced my son that I had actually hired that bully last year then he would never trust me again. It would undermine my character and trustworthiness and completely ruin our relationship. I am the helper and redeemer of my son’s bad situation, not the cause of it! How dare you even compare what I did to what you did!
 See the quotes from John Piper and John Calvin HERE. I am not suggesting a “Calvinist” must agree with John Piper or even John Calvin on every theological point in order to be considered a “Calvinist.” But if you are going to proudly promote this label shouldn’t you at least affirm the basic theological claims over the issues that make Calvinism so controversial in the church? The major reason we even know of John Calvin and “Calvinism” is because of his controversial views over predestination, election, free will, sovereignty, etc. If you cannot affirm his statements on at least those issues, then may I suggest you stop promoting the label “Calvinist?” Or, if nothing else, at least stop accusing people like myself of not really understanding Calvinism?
*Plus, the WCF does in fact affirm that “God from all eternity, did, by the most wise and holy counsel of His own will, freely, and unchangeably ordain whatsoever comes to pass…” and “Although God knows whatsoever may or can come to pass upon all supposed conditions; yet has He not decreed anything because He foresaw it as future, or as that which would come to pass upon such conditions.<link> This clearly indicates all creature’s evil intentions were “unchangeably ordained by God in eternity past” and this is not based on foreknowledge of future events.