This study analyzes how antipathy toward the slave trade spread in the British Atlantic world before the 1770s in the context of the transatlantic network of evangelicals; this network established a channel for the transoceanic communication which enabled Anglo-Americans to debate common issues. In the 1740s, this channel was used for discussion about the nature of the Great Awakening but the slavery issue gradually took up a substantial part of it as the slave trade increased toward the late eighteenth century. Anglo-American evangelicals who had antislavery tendencies could find a potential route to spread their thoughts and arguments into the Atlantic world by participating in these debates. However, the increased slavery debates on a transatlantic scale did not create the unitary antislavery community of evangelicals; instead, conflicting opinions on slavery were actively expressed in these transoceanic communications. It also stimulated the process collective memories of slavery to be shaped by pro and antislavery evangelicals within the evangelical network through voicing opinions on it for a long time. In studies by scholars over the past decades, it has seemed likely that a political movement for abolition was 'suddenly' began in the 1770s and in response to growing abolitionism, more aggressive proslavery arguments emerged. However, conflicts between pro and antislavery ideologies in the late eighteenth century resulted from common factors accumulated within collective memories which pro and antislavery evangelicals had shaped before the 1770s.