Ba'al Shem Tov, Esther 8/בעל שם טוב על התורה·מגלת אסתר ח׳

1One who reads the Megilah backward, has not fulfilled his obligation. (Mishnayos Megilah 2:1)That is, one who thinks that the miracles happened then (i.e. back in time), and not now, has not fulfilled his obligation.Divrei Shalom, p. 33c