"The beginning"

is simply that God exists and that he is the personal-infinite God."

Schaeffer goes on to say:

Our generation longs for the reality of personality, but it cannot find it. But Christianity says personality is valid because personality has not just appeared in the universe, but rather is rooted in the personal God who has always been.

The God Who Is There: near the start of the last sub-section of section 6, chapter 1.