Final answer:
The Renaissance philosophy that had a profound impact on early Christian reformers was Humanism, specifically Christian Humanism, which led to the Reformation through its call for personal piety and criticism of the Catholic Church.
Step-by-step explanation:
The philosophy of the Renaissance that influenced the thinking of early Christian reformers, contributing to the Reformation, was Humanism, particularly Christian Humanism. This movement emphasized the study of classical texts and early Christian writings to promote personal piety and moral reform, with a focus on the inner transformation of individuals rather than external rituals. Scholars like Desiderius Erasmus championed this form of humanism, which led to a criticism of the Catholic Church's practices and an eventual call for reform. The arrival of the printing press further disseminated these humanist ideas and criticisms, enabling reformation leaders like Martin Luther to challenge the church's authority and advocate for a return to the scriptural foundations of Christianity.