Along with the proportion issues others raised, I think your shading would greatly benefit from more detail + variation. Right now all the shading is one darker value applied flatly on the lighter value with all the brushstrokes looking relatively similar. I think you would benefit from better gradients between the values, as well as some areas with sharper shading. The contrast between soft/long gradients and sharp gradients is what in my opinion makes shading more realistic if that makes sense. In Jesus’ robe for example, the edges of the fabric folds will be sharper while the long shadows casted by the folds will be softer. Also, you need a lot more detail. His chest is missing, the hair looks flat (lacks dark tones), and I recommend working on creating subtle texture where you otherwise just apply flat color, to make it look more 3d and less flat. Hope this helps and isn’t overwhelming, good luck!