Towards the end of Spinoza's introduction he discusses who his intended readers are, and who would be better off not giving the book any mind:
(Brill, 1991, p. 56)
Such, learned reader are the topics which I here submit for your consideration, topics which I am sure you will find interesting by reason of the great importance of the issues discussed in the entire work and in each separate chapter. I would say more, but I do not want my Preface to expand to a volume, especially since its main points are quite familiar to philosophers. To others I seek not to commend this treatise, for I have no reason to expect them to approve it in any way. I know how deeply rooted in the mind are the prejudices embraced under the guise of piety. I know, too, that the masses can no more be freed from their superstition than from their fears. Finally, I know that they are unchanging in their obstinacy, that they are not guided by reason, and that their praise and blame is at the mercy of impulse. Therefore I do not invite the common people to read this work, nor all those who are victims of the same emotional attitudes. Indeed, I would prefer that they disregard this book completely rather than make themselves a nuisance by misinterpreting it after their wont. For without any advantage to themselves they would stand in the way of others for whom a more liberal approach to philosophical questions is prevented by this one obstacle, that they believe that reason must be the handmaid of theology. These latter, I am confident, will derive great profit from this work.
The final bolded sentences are of greatest interest to me. The opinions of Enlightenment savants and cultured despisers should be of little concern to serious theologians, but it is comforting to see that Spinoza- who was quite sensitive to religious life- recognizes what might be described as two tiers of religious thinking. He makes an interesting distinction between "the common people" and "others for whom a more liberal approach to philosophical questions is prevented by this one obstacle, that they believe reason must be the handmaid of theology." In a day when the theological imperative is usually understood as itself a sign of "fundamentalism" or "superstition", it's refreshing to read an assessment that recognizes the possibility for fruitful interaction between those who use reason, albeit in different ways with regard to the theological task. Unfortunately we remain heathens for Spinoza, who have still not quite seen the light of "a more liberal approach to philosophical questions."
I'm sure we're losing a ton of sleep over that. :)