Complex sentence: Christian denominations that baptize by affusion do not deny the legitimacy of baptizing by immersion or aspersion; rather, they consider that affusion is a sufficient, if not preferable, method of baptism.
Split into simpler sentences: Christian denominations that baptize by affusion do not typically deny the legitimacy of baptizing by immersion or aspersion. Rather, they hold the more modest view that affusion is a legitimate, if not preferable, method of baptism.