This is a way oversimplified statement. Each country has differing cultural and political dynamics, and an across-the-board demonization of firearms (or any weapon) shows a lack of understanding of this issue. Gun control laws are a complete failure in Chicago here in the US, where the criminals are the only people who now own guns. Gun homicides are through the roof in this gun-free city. Firearm-friendly cities and states don't reflect those statistics the same way.
In England, knife violence was at record levels in 2020, reflecting that violent and mentally ill people will use whatever weapons are available to them. So should all knives be banned in England? Believe it or not, some politicians have offered that as a solution. The TSA at the airport security checkpoint confiscated my fingernail clippers a few years ago while boarding my flight, fearing I might hijack the plane with them. That's insane. This line of logic has no end to personal encroachment on our liberties.
I agree with you that the far majority of criminals and mentally ill people are not going to read the bible and change their ways, but neither are they going to follow gun control laws.