people 主语
who believe that they are fighting a just war 定语从句
who做定语从句的主语,believe谓语,that从句是believe的宾语从句
act aggressively 谓语
while those who believe that they are fighting an unjust war do not.
while引导的并列句（轻微转折）
those 主语
who believe that they are fighting an unjust war 定语从句
do not.谓语
认为他们在进行一场公平战争的人们,表现激进/积极,而那些认为他们在进行一场不公平战争的人们表现不激进.