A cross is just a symbol - it is not worshipped, that would be idolatory. It's a way to recognise Xians easily just as a fish still is today. Leaglebeagle, if you were to give up your child to save someone else I suspect it wouldn't matter as to the method of execution, the pain and grief would be intolerable for you. It's not in the amount of suffering physically so much as the separation from God that is amazing, it's just easier for us mere mortals to focus on something tangible.