Some folks are not happy about this. They would deny to God the right to do with his creation as he sees fit. They do not think it is fair that God would create some vessels for wrath (usually there is no complaint about people being created as vessels for mercy).
Others are not quite so bold as to complain about that. They tack a slightly different tack. They suggest that God is unfair in picking some rather than others without reference to something about the person himself. They argue that this is arbitrary which, they think, makes no sense or is unjust.
One comment that seems to come from this perspective of complaint against the Biblical model of sovereignty is a comment I recently read from GodIsMyJudge. Criticizing the Calvinist view of election, he stated:
But whatever God’s other reason was, it couldn’t be related to some good quality or disposition in us. Let’s say I am building a house and need one nail. Even though my end goal is to build the house, I would still pick longer nails over short ones if the job called for it. In that case longer nails are more suitable for my purpose, so this example can’t be representative of unconditional election. But if any nail will do and all the nails are the same, then I don’t care which one I pick out of a jar full of nails. So in this way, whatever the other reason is, it doesn’t explain why one was chosen and another rejected.(source)
This kind of criticism has a patina of validity: wouldn't a good carpenter pick the best nails for the job? Of course he would! He wouldn't pick short nails where long nails would be better, or vice versa.
The problem with the example is that it treats God as finding men as pre-existing objects. It is the problem that lies beneath the error of Molinism and middle knowledge.
Both Molinism and this analogy treat God as essentially "finding" men "as is" and then basing his decrees on that which did not come from Him. This is contrary both to the Scriptural analogy and to sound reason.
The Scriptural analogy is that of a potter. The potter begins with clay, not nails of a previously (and externally) determined length. He builds the pots according to the purposes he has for them, not the other way 'round. He does not build a pot and then think, "Hmm ... this would make a nice vase" or "Hmm ... looks like this is going to have to be an ash-tray." God does not create at random and then make do with what luck or fate gives him. He does not simply roll cosmic dice. No, God makes pots the way he wants them to be.
This contrasts with the analogy of a carpenter building a house who simply finds himself with some short nails and some long nails and makes the best of what he finds. Of course, that analogy itself conflicts with sound reason.
If a carpenter were going to build a house he would not (unless forced to) simply resort to a bag full of a random assortment of nails. Instead, a reasonable carpenter would plan ahead and count the costs and so forth before he begins. He doesn't want to build half the house only to find out that he doesn't have enough long nails to continue.
No, instead a wise (and sufficiently well-funded) carpenter would purchase suitable materials for the purpose in advance. He would figure out how many long nails he wanted and purchase that number - same for the short nails.
But Molinism and the analogy GodIsMyJudge provided make God out to be an underfunded carpenter, making the best of the hand that's been dealt him, as it were. Recall that in Molinism God does not decide how a man will react to particular circumstances, he simply discovers this fact via middle knowledge. He then makes the best of men's choices - they dictate the size - and perhaps shape - of the house.
In this scenario, God considers himself lucky that there are so many people who choose to believe, which gives him that many more longer nails. The longer nails, you see, are differentiable from the shorter nails not by the choice of the carpenter but by their own choice: it is something they did, not something they received.
But that's not the way of Scripture. Scripture declares:
1 Corinthians 4:7 For who maketh thee to differ from another? and what hast thou that thou didst not receive? now if thou didst receive it, why dost thou glory, as if thou hadst not received it?
Not even faith fits that bill, for it is the fruit of the Spirit:
Galatians 5:22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
Thus salvation, including faith, is called the gift of God:
Ephesians 2:8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
So, even our faith is something we receive - it's not something of our own that differentiates us from another. We are what we are by God's grace. He is the potter and we are the clay.