The study explores semantic and syntactic parallelism grasped through different types of repetition. Rygiel (1994) and Fox (2014) models are selected for identifying parallelism and lexical repetition in a valuable book of a philosophical doctor who mixed science with faith and became one of the most famous intellectual scientists in Egypt. Dr. Mostafa Mahmoud's A Dialogue with an atheist is the core of this study. It is an imaginary intellectual dialogue between the author and an atheist who arose many skeptic questions about faith. By answering these questions, Dr. Mostafa Mahmoud proved that science gives a real power not compared to the divine knowledge. Semantic parallelism identified through synonymous parallelism (54%) and antonymous parallelism (46%). Syntactic parallelism involves sentence (18%), clause (13%), phrase [Noun phrase (44%), Verb phrase (36%), Prepositional phrase (16%), and Adjectival phrase (4%)]. Seven types of repetition including anaphora (34%), mesodiplosis (21%), polyptoton (14%), epistrophe (13%), tautotes (13%), anadiplosis (2%) and chiasmus (1%). It was found that repetition is used to emphasize a point, approve a fact or idea, exhibit objectivity and create cohesion. Each repeated word carries a crucial idea and it cannot be considered redundant. Parallelism makes text symmetrical and memorable for the reader and creates artistic balance. It reflects the author's creativity. Z-test is used to analyze the data. The analysis has proved that there is a statistically significant difference at the level of (0.01 %( between parallelism and repetition in favor of parallelism which constitutes (79%) and repetition (21%) and z value (18.62)