Archimandrite Seraphim Aleksiev writes,
Grumbling is like the autumn hoarfrost which, when it falls, destroys all the labors of the gardener. Few people realize how bad grumbling is for the soul. Almost everyone considers it to be a small sin, but even though it seems so, it has very grievous consequences. In the autumn before the hoarfrost falls, the experienced gardeners notice the signs of the coming cold weather and urge their young helpers to gather the peppers and the tomatoes. the young ones laugh: “Why should we gather them? the weather is still so nice!” Then the next morning they see the first frost has come over the gardens. They pick up a pepper and take a bite to taste it, but it is as bitter as poison and cannot be eaten. Thus their small carelessness has destroyed all their labors. In the same way grumbling withers all the virtues of the soul and makes bitter and useless the fruits of suffering.
Why is this so dangerous? God gives us difficulties and problems to help us come closer to Him. This is His only aim. He wants us to be united with Him. But when something is not just how we like it, we grumble instead of giving thanks to God. You see, we turn away from Him rather than towards Him to seek strength and direction. This is the danger of all our grumbles. When we grumble we have separated ourselves from God. When we grumble we are not pleasant to others. As Alekiev says, “grumbling withers all the virtues of the soul.”
Not grumbling, but patience in suffering––this is what God wants from us. “In your patience possess ye your souls” (Luke 21:19), the Savior has instructed us, because “we must through much tribulation enter into the kingdom of God” (Acts 14:22). Into this Kingdom of God one cannot enter with pride which teaches us to grumble, but with humility which makes us patient. There are no greater teachers of patience that sorrows. This is precisely why God sends us suffering: so that we will humble ourselves before Him. No one has been saved by pride, because “God resisteth the proud, and giveth grace to the humble” (1 Peter 5:5). The doors of the Kingdom of Heaven are too low and narrow for the proud to enter through them; only those humbled by the sufferings of life can go through them freely.
I cant tell you how often my wife and I will find ourselves in the car on the way to church grumbling about so many little things. When we are lucky, one of us catches our plight and says, “Let’s thank God.” This always awakens us to our sorrowful state.
A good exercise is to examine your grumbles – just for one day. Look at what it is you grumble about and reflect on why God set this discomfort in front of you. See if you can find a way to give thanks to God for all He sends you. How can you draw strength from your relationship with Him. I think you will find this to be a rewarding exercise.
Remember, God did not promise us that we would not have difficulties. But He did promise that He would give us help and comfort.
“In the world you have tribulation; but be of good cheer, I have overcome the world.” (John 16:33)
Ref: The Meaning of Suffering and Strife & Reconciliation, p 35, 39