Concerning the Short Treatise on God and Man and His Well-Being – Chapter VI, on divine predestination

In Spinoza's words – How is it possible that God, who is said to be supremely perfect, and the sole cause, disposer, and provider of all, nevertheless permits such confusion to be seen everywhere in Nature? Also, why has he not made man so as not to be able to sin?

Now, in the first place, it cannot be rightly said that there is confusion in Nature, since nobody knows all the causes of things so as to be able to judge accordingly.
This objection, however, originates in this kind of ignorance, namely, that they have set up general Ideas, with which they think, particular things must agree if they are to be
perfect.

As regards the other [objection], why God has not made mankind so that they should not sin, to this it may serve [as an answer], that whatever is said about sin is only said with reference to us, that is, as when we compare two things with each other, or [consider one thing] from different points of view. For instance, if some one has made a clock precisely in order to strike and to show the hours, and the
mechanism quite fulfils the aims of its maker, then we say that it is good, but if it does not do so, then we say that it is bad, notwithstanding that even then it might still be good if only it had been his intention to make it irregular and to strike at wrong times.

We say then, in conclusion, that Peter must, as is necessary, conform to the Idea of Peter, and not to the Idea of Man ; good and evil, or sin, these are only modes of thought, and by no means things, or any thing that has reality, as we shall very likely show yet more fully in what follows. For all things and works which are in Nature are perfect.

Comment:

Spinoza objects to the notion that Nature is chaotic.  We don't know all her ways and therefore it only seems chaotic.  This is a point made in his Ethics.  Here he adds a consideration of sin.  His point of view is that sin is a relative notion in our minds and is not something that is real.  It is a result of our limited knowledge in comparing things.  Since Nature is perfect and sin would be an imperfection it must be a defect in our understanding.