In regards to the question, does Descartes appear to be a sceptic? I see so plainly that there are no reliable sings by which I can distinguish sleeping from waking that I am stupefied - and my stupor itself suggests that I am sleep! He acknowledges that sometimes the senses can deceive, but only with respect to objects that are very small or far away, and that our sensory knowledge on the whole is quite sturdy.
According to the First Meditation, God is perfect: he does not deceive and as God leads us to the material world which physically exists, therefore God must exist. One can see this in a typical IMAX theaters around the world, where they attempt to reach this virtual reality. While we can doubt studies based on composite things, like medicine, astronomy, or physics, he concludes that we cannot doubt studies based on simple things, like arithmetic and geometry.
In the end of the First Meditation, Descartes sees it as impossible to stop from thinking about these theories, he then tries to believe that his opinions are not true.
Questioning, having thoughts or even thinking out of the Catholic Church doctrine could be punished by imprisonment or even death.