Corrosion is the gradual destruction of materials (usually metals) by chemical reaction with the environment and the most common example of this is rusting. Rusting (more formally the oxidation of metals such as iron) takes place when the metal reacts with the oxygen in air to form an oxide. Most metals are elements which tend to lose electrons when they are involved in chemical reactions and form ions (charged elements). Metallic ions, because they are formed from atoms that have lost electrons, are positively charged.
A common oxidation reaction in corrosion is the oxidation of neutral iron atoms to positively charged iron ions:
Fe » Fe+2 + 2e–
The electrons lost from a metal must go somewhere, and they usually end up on a nonmetallic atom forming a negatively charged nonmetallic ion. Thus, the full chemical equation for the formation of rust is:
Iron + water + oxygen 
rust
4 Fe(s) + 6 H2O(l) + 3 O2(g) 4 Fe(OH)3(s)
Iron(III) hydroxide, Fe(OH)3 then dehydrates to produce Fe2O3.nH2O(s) or rust.
At this point, all but the scientists amongst us are probably bored or wondering what this chemistry lesson has to do with a church blog. I suppose these meditations arose from considering how easy it is for us to react with our environments, how we are called to be distinctive salt and light in our communities, but how we often take on the qualities of the culture around us rather than allowing God’s light to shine through us. We are urged to shine like stars in the sky, holding firmly to the word of life (Phil 2:15-16), yet so often we allow the attitudes and values of the world to corrode us.
An iron chain is bought and looks shiny and bright:
If it is left to the elements, however, rusting will occur at some point, radically changing the appearance of the chain:
That same kind of deterioration can occur in us if we allow ourselves to be exposed to the world’s attitudes without being renewed by God’s Spirit. The word ‘corrosion’ itself comes from the Latin word meaning ‘to gnaw’ (think of how a corrosive acid burns skin, for example).
Often, we allow attitudes and beliefs to gnaw away at us, robbing us of the peace, joy and hope which God has promised. Hebrews 12:15 warns against a bitter root growing up within us which, if allowed to grow unchecked, will defile many. When we allow resentment, bitterness, unforgiveness or any other wrong attitude to find a lodging place in our hearts, we allow a corrosive effect into our souls which can lead to our ruin. In the world, there are many methods employed to prevent corrosion: plating, painting or the application of enamel, for example, which work by providing a barrier of corrosion-resistant material between the damaging environment and the structural material. We too need to find methods which prevent the corrosion of our souls: washing with water through the word (Eph 5:26), being cleansed through repentance and forgiveness (1 John 1:8-9), refusing to let the sun go down on our anger (Eph 4:26-27) and thereby not giving the devil any foothold in our lives, forgiving freely (Matt 6:14-15), living in trust rather than anxiety. (Matt 6:25-34) Such antioxidants work to keep us spiritually healthy and strong. Antioxidants are widely used in dietary supplements these days and have been investigated for the prevention of diseases such as cancer, coronary heart disease and even altitude sickness. Let’s be as concerned about our spiritual health as we are about our physical health and work on developing the grace-attitudes Jesus demonstrates as being the prevention to corrosion of the soul.