doubting Thom·as 
/-ˈtɑ:məs/ noun
plural ∼ -as·es /-ˈtɑ:məs/ noun [count] somewhat old-fashioned : someone who rarely trusts or believes things before having proof : a doubtful or skeptical person
▪ She kept trying, hoping to prove all those doubting Thomases wrong.
▪ She kept trying, hoping to prove all those doubting Thomases wrong.
