29 Let no unwholesome word proceed from your mouth, but only such a word as is good for edification according to the need of the moment, so that it will give grace to those who hear. 30 Do not grieve the Holy Spirit of God, by whom you were sealed for the day of redemption. 31 Let all bitterness and wrath and anger and clamor and slander be put away from you, along with all malice. 32 Be kind to one another, tender-hearted, forgiving each other, just as God in Christ also has forgiven you. Ephesians 4:29-32 (NASB)
Steel is made through the smelting of iron ore. Iron becomes steel as carbon is added while the iron is very hot. What makes steel much harder than iron was not really understood by the ancients who created it. All they knew was that at a certain point in the shaping of a sword they would lay the red hot blade into the coals for a few minutes then resume the process of hammering, cooling in water, re-heating, hammering, cooling in water, et cetera. The finished product was a sword that would not bend in battle and could be sharpened over and over. The blade was actually made up of many pieces of iron rods that were heated, flattened, and folded upon itself over and over. It was hard work, but that was what it took to create a fine, usable steel sword.
17 Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come. 2 Corinthians 5:17 (NASB)