I don't believe making it a sponge or glass is good. But if I had a choice I would rather have a sponge soaked in the love and truth of God where I am not so easily offended when my faith is attacked. Glass brakes easily. But better than a sponge or glass is to ask God for a heart of flesh. He said he would take out our heart of stone and replace it with a heart of flesh. May God give me a heart of flesh in Jesus name.