Daniel felt that Marvin must be the least god-fearing human in the world.
The unknown is always mysterious; to other believers, the Goddess of Truth, Eunia, must have been born from Truth itself, a deity to guide them. But in Marvin's eyes...
Eunia is just Eunia, even if she is a deity, she is still Eunia, a little child over three years old.
Marvin, having personally created a deity, would have to be haunted to feel awe towards such an existence....
Perhaps when he first met Eunia, Marvin had been somewhat at a loss, unsure of how to treat a god, so he chose to send Eunia to the orphanage and wanted to observe the 'god's' reaction.
If Eunia had some purpose, then after being abandoned, she would have made some peculiar action, but she did not; from beginning to end, she behaved like a child abandoned by her father.