"And here, too, is the great cause of mental weakness and inefficiency. In turning from God's word to feed on the writings of uninspired men, the mind becomes dwarfed and cheapened. It is not brought in contact with deep, broad principles of eternal truth. The understanding adapts itself to the comprehension of the things with which it is familiar, and in this devotion to finite things it is weakened, its power is contracted, and after a time it becomes unable to expand. COL 41.3"
"For to be carnally minded is death; but to be spiritually minded is life and peace."
EGW's statement about mental weakness resulting from focusing on uninspired writings parallels the idea in Romans 8:6 that being carnally minded (focused on earthly things) leads to death, while being spiritually minded leads to life. Both passages contrast earthly and spiritual focus.