Before we start this tutorial download these brush sets and install them ready.
Create a new document 600x600 pixels, select the pen tool and create half a cross like this.
Right-click and goto "fill path" fill the path with the color black, right-click once more and goto "delete path". Duplicate your layer then flip it horizontally by going to "edit > transform > flip horizontal". Move the cross side by side then merge the layers together.
When moving them side by side make sure theres no line in the middle as this will cause problems when adding the layer styles. Select the elliptical marquee tool and create a circle like the image below.
Hit the delete key to make a cut into the cross, DO NOT clear the selection, move the selection and position it into the corners where the stakes meet hit delete each time, the result were looking for is in the image below.
Now were going to add the layer styles, this is where the cross takes shape.
You should end up with this.
With the swirls brush begin to add your swirls, add this layer style to all the swirls.
Carefully build up your layers of swirls untill you have something like this.
Select your cracks brushes and add some cracks to your cross.
Thats it all done, with some more imagination you could end up with something as simple as this.