The subject of this research is the correlation of personality traits of people who have changed their attitude to religion after the age of 16: the level of intolerance/tolerance for ambiguity, the level of orientation to social desirability and the level of agreement with parents` beliefs depending on course of changes. The research sample consisted of 492 people from 16 to 69, 102 of which answered questions in person, whereas others - via Internet forms. The results showed that religious people have significantly higher level of intolerance for ambiguity, orientation to social desirability and agreement with parents` beliefs on religion and significantly lower level of tolerance for ambiguity. Stepwise binary logistic regression showed the following results in the sample on the whole: whether a person will become religious or not as an adult can be predicted in the first step by  agreement with parents` beliefs on religion, in the second step – by the level of intolerance for ambiguity and in the third step – by the level of orientation to social desirability. However, the record of course of attitude changes to religion showed that when switching from disbelief to belief, more contribution is made by attitude to ambiguity: by the level of intolerance for ambiguity for men, the level of tolerance for ambiguity for women, and in terms of faith preservation – by agreement with parents` beliefs on religion. People become religious rather attempting to avoid ambiguity of situation, and remain religious mostly in agreement with parents` position.