Final answer:
John Locke's assertion that we can be most certain of our own existence and the existence of God reflects his philosophy that knowledge derives from experience and that consciousness forms the basis of identity, with God as an integral part of reality.
Step-by-step explanation:
John Locke's claim that the two surest things we can know to exist are ourselves and God suggests a foundational aspect of his philosophical thinking. Locke's thesis in An Essay Concerning Human Understanding asserts that humans are born with minds as a blank slate (tabula rasa) and that all knowledge comes from experience, which includes both sensation and reflection. This idea supports his belief in self-awareness and consciousness as the basis of individual identity, rather than biological essence, and positions God as an intrinsic part of the understanding of existence within his empirical framework.
Locke's concept of self-knowledge closely aligns with his psychological continuity approach to identity, which claims that memory and consciousness are key to personal continuity over time. Such an approach promotes the principle that our intrinsic sense of being and introspection provide a more substantial claim to self than any purely physical or biological basis could. Moreover, Locke's religious convictions led him to argue that the existence of God is evident and necessary, inferring that the divine plays a continuous role in confirming the existence of things, as alluded to by other philosophers such as George Berkeley.