You believe with your generation

The protagonist, Philip, who was born with a club foot, moved in with his uncle Mr. Carey, the Vicar of Blackstable after his mother's death.
He dropped out of King's School at Tercanbury, came to Germany, and stays at the Frau Professor Erlin's lodging house with several guests.

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"But why should you be right and all those fellows like St. Anselm and St. Augustine be wrong?"
"You mean that they were very clever and learned men, while you have grave doubts whether I am either?" asked Weeks.
"Yes," answered Philip uncertainly, for put in that way his question seemed impertinent.
"St. Augustine believed that the earth was flat and that the sun turned round it."
"I don't know what that proves."
"Why, it proves that you believe with your generation. Your saints lived in an age of faith, when it was practically impossible to disbelieve what to us is positively incredible."
[Of Human Bondage by Somerset Maugham]
I'd like to know what "you believe with your generation" means.
Thank you in advance for your help.