A common sentiment from atheists is that they won’t believe in things that can’t be shown.
We cannot see it, we can’t touch it. In the case of electromagnetic devices it is not always there. Yet one can observe its effects being inline with a given theory.
So is it believed in?
Atheists "can" believe in magnetism based on its effects.
Atheists don't feel that there are affects that can only be attributed to God.
Once could argue that a man named Atlas is holding up the world. But that begs the question, what is holding up Atlas. The answer is that he is standing on a giant turtle. But what is the turtle standing on (etc).
It is much like a Superman movie in which Superman caught Lois as she was falling from a tall building and he said "Don't worry, Lois, I've got you." Then Lois said "you've got me, but who has you?"
There are an infinite number of things to speculate about, but they likely are not all true (we could speculate that Santa exists).
But, if we take careful measurements of magnetism, and see how it interacts with other variables, we can write formulas about them.
If you had three equations, and they all had three variables, you could solve for one variable at a time. So, you could determine, for example, x, y, and z.
James Clerk Maxwell was teaching a high school class when he wrote the four known laws of electromagnetics, and noticed that there were four variables. This, he thought, might mean that two of the equations might be linearly dependent. For example, x + 2y = 3z, and 2x + 4y = 6z are really the same equation (one is twice the other).
When Maxwell tried to find out which of the two electromagnetic laws are duplicates, he ended up showing that any three will derive the fourth. Thus, there are no unnecessary laws, but they all are interdependent.
The science of electromagnetism started with careful measurements, from which we derived formulae, and we found that 4 of the formulae are co-dependent on each other.