Since God makes it plain that not all will be saved then His purposes can be thwarted? Who wants to belong to a God who isn't powerful enough to do what He purposes?
Say you are planning a great party, no expense spared and you have reason to believe this one or that one may not be able to attend but you desire all to be there because you love them. Then someone tells you, I hear someone isn't coming to your party and you invited them. Well, I'm not going to a party given by you, the host, because your purpose was thwarted and what a looser you are.
Just bringing it down to your level so you have some idea how your reasoning sounds.
I'm in amazement at how mortal men with their little minds can question The Almighty. You are way too puffed up. Let's put it this way, you couldn't take your next breath without the mercy of God. How's that for 'isn't powerful enough'? That will take your 'puff' away.
That's why hell was created for those who don't want to belong to Him. Satan was puffed up, he felt he was better than His Creator. We all get what we search after.
It seems to me you are the one questioning God's purpose of election; trying to explain them away with man-made terms like "respecter of persons." Everyone is under God's rule. Pagans deny it, but they are nonetheless under his rule.