Skeptic

A skeptic (also sceptic) is one who questions the validity of a position until shown to their satisfaction that the position is warranted. The nature of what can convince a skeptic will vary from person to person. One whose philosophy on life leads them to be a skeptic by lifestyle is said to practice skepticism.

The term "skeptic" is often abused in a religious context by atheists and agnostics, claiming there is insufficient evidence of God's existence but not being at all sceptical about their own atheistic beliefs for which there is no evidence at all.

"Doubting Thomas" in the Bible is an early example of a sceptic, as he did not believe that Jesus had risen until he saw Him with his own eyes and put his fingers in the wounds on Jesus' body.

See sceptical - The Free Dictionary.