The teaching of the Catholic Church confirms the insight of the Buddha. A Catholic Christian is obliged to do what you describe: "study a teaching, pray for guidance, and make up his or her own mind."  Having done that, and having arrived at a judgement of conscience, a person is obliged to follow that judgment even if it is objectively wrong.  The Catechism of the Catholic Church at #1790 puts it this way:  "A human being must always obey the certain judgment of his conscience. If he were deliberately to act against it, he would condemn himself." Strong stuff.
Even the most conservative reading of the Catholic tradition affirms the supremacy of conscience. To reduce conscience formation to blind obedience is to strip conscience of any meaning or value.  You're right: this is the work of adult believers.