Solipsm is an old idea. How can I believe what I see is real?
there are yet many other of their informations (presentations), of the truth of which it is manifestly impossible to doubt; as for example, that I am in this place, seated by the fire, clothed in a winter dressing gown, that I hold in my hands this piece of paper, with other intimations of the same nature. But how could I deny that I possess these hands and this body, and withal escape being classed with persons in a state of insanity Descartes Meditations 4.
God could relieve the doubting Descartes from his insanity. God would never let him be so deceived. That is what we are here for: to lead people to God. People need a spiritual awakening. Without it they are doomed to fall into delusion and fantasy.
9. Nevertheless, the belief that there is a God who is all powerful, and who created me, such as I am, has, for a long time, obtained steady possession of my mind. Descartes Meditations