What do you believe?

Duck.
Block.
Twist to the left.
Thrust.
Block.
Duck.
*WHAM*
"Ow."

Bruce and Diana were sparring.  Bruce was being beaten badly.

The three floors underneath Bruce's penthouse in Wayne Tower were entirely empty, and therefore the perfect place to train.  In the 18 hours since Diana had agreed to train him, Bruce had had everything they'd need shipped into the tower: floor pads, training weapons, etc.  Diana was impressed with his eagerness to learn. She was less impressed, however, with his actual skill.
"Your stance is too narrow, and you're locking your knees."
Bruce shifted his stance accordingly, fighting the urge to give her a spiteful glance.
"That's better," she said, giving him an approving smile.

At the moment, they were training with wooden staffs.  Normally Diana wouldn't have started with something so advanced on a student's first day of training, but she thought it might be fun.

They stood about ten feet apart, staring each other down.  Bruce looked at Diana with determination and a strong hint of repressed anger.  Diana met his gaze with casual bemusement.
Bruce became impatient, charging straight at her.  He abruptly stopped about three feet in front of her, twisting to the left and jabbing his staff towards her stomach.  Diana was surprised at his rather effective maneuver, but she was more than skilled enough to counter it.  Twisting her own weapon underneath his and wrapping it in-between his arms, she flipped him around in a complete backwards somersault, slamming him back-first onto the floor.

She stepped back and stood over him, slowly twirling her staff in one hand.
She was toying with him, and he knew it.

"Are you going to toy with me, or actually teach me something?" he asked.
She replied sternly and forcefully.  "Amazons teach through example. We don't 'start easy;' we fight hard."
Bruce moved to attack again, and was soundly thrown to the ground yet again.
"A real foe won't 'go easy on you.' Neither will I.  If you expect to be able to learn anything real, you're going to have to learn to fight a real opponent."

Bruce halfway sat up and glared at her over his left knee.
She almost chuckled at him, and let herself relax back into a casual stance.  "Maybe you should just pray to Athena for help."
He gave her a quizzical look. "Athena?" he said with an edge of sarcastic disbelief.
"Yes; Athena," Diana said matter-of-factly.
"The goddess Athena?"
"Is there another one?"
Bruce stood up and rubbed his forehead with his hand.  "Athena is a myth."

Diana scowled at him.  "Athena is the one who gave me life. Does my very existence not prove hers?"
Bruce raised one eyebrow at her.  "No, it doesn't. Athena didn't give me life, and I'm here, too."
Diana stood up a bit straighter.  Taking her staff in both hands, she held it horizontally and effortlessly snapped it two.
"I am not you."

Bruce decided that it wasn't worth arguing with her.  "Fine; believe what you want," he said as he turned back toward the far wall to get a new staff.
Diana felt a wave of sympathy for her friend: was he entirely without belief?
"Bruce..." she gently called out to him, "what do you believe?"
Bruce stopped for a moment, still with his back to Diana.  He slowly let his head hang down.

"...I don't know."