VS
The bat symbol, the emblem worn on the chests of Batman and many of his allies, as well as the beacon that shines over the Gotham skyline on a nightly basis, represents one thing : justice. When the people of Gotham see a costumed vigilante displaying a bat symbol, they know that they are safe; that justice will be served, and the evil stopped (at least for the night).
The cross in Christian mythology also holds a lot of significance for its practitioners, many of these ideas could also be said for what it is that the bat symbol stands for.
The idea that the cross is the center of the story in scripture, meaning “A Bible without a cross is a Bible without a climax, a Bible without an ending, a Bible without a solution [...] In Jesus’s body, he took on the sin of the world and paid the price of all humanity. At the cross the new Adam, Abraham, Moses, David arises to create a new humanity, family, and kingdom [...] Wisdom was found not beyond the cross, not above the cross, not below the cross, but in the cross.” (https://www.crossway.org/articles/10-things-you-should-know-about-the-cross/)
Without the bat symbol there’d be no Batman, and without Batman there would be no story, so the idea of the bat symbol being the center of the story is present in the narrative.
After the death of his parents, Bruce also decided to uphold the justice system in Gotham single handedly; hence he “took on the sin” of the city, and made it his mission to create an ideal Gotham.
When it talks about Abraham, Moses, David, and others continuing Jesus’ work under the guide of the cross, it fits in well with the sidekicks and allies of Batman working underneath his logo to try and uphold his ideals. In this sense the wisdom found in the bat is parallel to that that could be found in the cross.
The cross redefines power in the kingdom. “Jesus comes as the true Son and redefines power by displaying strength through weakness. He does not exploit his power like Adam, but empties himself [...] He becomes a servant of all, and thereby is exalted as ruler of all.” (https://www.crossway.org/articles/10-things-you-should-know-about-the-cross/)
Batman wants to bring salvation to the people of Gotham. He is aware that there is a power-dynamic at play, and that it is in his favor, but never exploits the power that he holds.
He works endlessly to serve those that he protects and expects nothing in return, according to the article this is the same mindset Jesus had towards his people.
The cross is stated to bring peace, reconciliation, and unity; “Reconciliation for the world, peace, shalom, and unity comes only by the blood of the cross [...] No blood means no harmony.” (https://www.crossway.org/articles/10-things-you-should-know-about-the-cross/)
The bat symbol represents the bringing of peace and reconciliation of evil in Gotham City.
Any one who wears the symbol understands that the only way to bring about this everlasting peace is to fight tooth and nail against the criminals who wish to disrupt it.
Thus the idea of “no blood, no harmony” is also a perfect fit for the comic universe.
When talking about why Christians make the sign of the cross on their bodies it says, “This sign is not just ritual performance but active participation in the narrative of salvation enacted in the liturgy. In continuously making this marker of identity on our bodies, we are formed in self-gift, the ultimate act of which we celebrate at Mass. We offer ourselves in liturgical prayer, participating in Christ’s kenotic act and making meaning of our existence in light of the Incarnation.” (https://churchlifejournal.nd.edu/articles/the-mass-for-millennials-sign-of-the-cross/)
This could ring true also as to why Batman & Co. proudly display a bat across their chests.
When they are in costume they are offering themselves up to the city. They are no longer regular people, they are just guardians of the night.