Grumbling seems to be a natural habit; most people do it a bit, while some make it their trademark. But God sees it differently. In the wilderness 14,700 people died on one occasion because they grumbled (read the fascinating story in Numbers 16:1-50). Their death was a warning to Israel, but Jesus also warns the disciples (John 6:43). Paul affirms the same warning to the church in 1 Corinthians 10:10; so does Peter (1 Peter 4:9), and Jude (Jude 16). The Bible tells us that grumbling is a bad business, which God will punish.

'Grumble', in English, comes from an old Dutch word meaning 'to mutter'. Although four different Greek words are translated 'grumble' in the NIV, they convey similar ideas of low key, low volume, murmuring discontent directed against others. Deuteronomy 1:27 says that the Israelites grumbled in the tents. It was a complaint they did not initially express publicly but was fermented in their domestic environment until it generated such a momentum that it spilled over to defile many. That was recorded in the hymn-book of Israel to warn worshippers of future generations that grumbling is the smouldering fuse of disbelief which has the potential to wreck the community: God is angered by it (Psalm 106:25).

Those who are skilled in grumbling, ensure that they spread their discontent quietly so that their contribution does not stand out from the crowd. In the Numbers 16 story, the grumbling started with 3 main people, but in the end almost 15,000 had taken part. Grumbling has all the hallmarks of Satan's subtle, and apparently 'concerned', lies against God's character (Genesis 3:1-5). Those who grumble, slander God's sovereign love. They also slander His sole right to be the Judge of all people, by arrogantly presuming the right to judge others; oblivious of the fact that they are accountable to the Lord who will judge them (Matthew 7:1). The Bible teaches us that God knows each grumbling heart as well as every grumbling word, showing His wrath in judgement.

Alas, grumbling is a contagious disease. A few muttered words of discontent can soon spread like a forest fire (James 3:5-6). In the same way that sin crouches in the darkness waiting to strike (Genesis 4:7), so muttered words lie in the back of people's minds until an opportunity comes to unseat an enemy (James 1:13-15). That is why we need God to speak to us about it, so that we can recognise our sin, repent and start a new mouth-style - and the same applies to social media, texts and emails. Especially, we must not mutter about fellow Christians, and if we hear it we should rebuke it. What we learn in the church will prepare us for life at work: however, if we learn grumbling from other believers, we will do the same with our work colleagues. What a shameful way to deface the gospel of God's grace! So, if you are doing it, repent and stop. Grumbling is not a private sin, it affects others. So, confess it to other believers and ask to be accountable to them, before you start a fire that you cannot stop.