Christ never meant that we were to remain children in intelligence: on the contrary, He told us to be not only "as harmless as doves," but also "as wise as serpents." He wants a child's heart, but a grown-up's head. He wants us to be simple, single-minded, affectionate, and teachable, as good children are; but He also wants every bit of intelligence we have to be alert at its job, and in first-class fighting trim. The fact that you are giving money to a charity does not mean that you need not try to find out wheether that charity is a fraud or not.
C.S. Lewis, Mere Christianity, p. 75