Skepticism

An undecided, inquiring state of mind; doubt; uncertainty.

The doctrine that no fact or principle can be certainly known; the tenet that all knowledge is uncertain; Pyrrohonism; universal doubt; the position that no fact or truth, however worthy of confidence, can be established on philosophical grounds; critical investigation or inquiry, as opposed to the positive assumption or assertion of certain principles.

A doubting of the truth of revelation, or a denial of the divine origin of the Christian religion, or of the being, perfections, or truth of God.

the disbelief in any claims of ultimate knowledge

doubt about the truth of something