Final answer:
The statement in question aligns with the philosophy of Søren Kierkegaard, emphasizing the need for existential commitment to God to realize genuine Christian faith.
Step-by-step explanation:
The statement referring to the necessity for an existential commitment to God amidst life's challenges and paradoxes, to validate one's Christianity beyond mere intellectual assent, is most closely associated with the work of Søren Kierkegaard. His existential philosophy heavily emphasized the subjective nature of truth and the importance of personal experience and decision in matters of faith. Kierkegaard argued that true Christian faith required a 'leap of faith' and a commitment that transcends rational understanding, an idea that reflects the complexities and paradoxes of human existence.