One thing I've found to help minimalize colors is to pick a range of shades, and replace it with the average of those shades. For instance, the skin tone used on the face and arms, or the red of the arms and legs. If you have a "fill all" tool, you can replace the skin tone with a color of high contrast (like green), then select all of the skin tone colors and make them green. To finish, replace the green with the average skin tone, and now you've converted the fifty shades down to just one. Maybe that helps, that's what I do when my art studio gives me a billion shades of the same color. Also might suggest a more complimentary background (though the yellow is quite eyecatching). Other than that, love the design for the cross, mixed with the reds and blacks. Not enough crucifixes I've seen catch the reality of His suffering, but somehow you manage to communicate it in a 66x99 portrait perfectly.