To GIVE BIRTH in passive mode
One way of doing this is to use the verb bear for "give birth to"
- formal, literary
Give birth to (a child)‘she bore six daughters’
— Lexico
This takes the past participle born or borne.
It's slightly peculiar because for your use it needs the preposition of rather than by:
They pray for help from idols, born of frightened minds.
The reason for using of is that with by, born/borne takes its usual meaning of carried. Of changes its meaning to the "give birth" sense, as shown in MW's definition for born of necessity.
It may be better to lose the comma and have "born of frightened minds" as a postpositive adjectival phrase:
They pray for help from idols born of frightened minds.
... that is, "idols which were born of frightened minds."