When St Augustine of Canterbury (who died in 604 ad) was asked to define time, he replied : “If no one asks me what time is, I know. If I want to explain it to anyone who asks me, I am at a loss.” Integrity is very like that for me; but let's look at it under two main headings before we try to agree about why it is such a key part of life and leadership generally, and of Christian leadership in particular.

Integrity is what other people value in you as they observe you seeking to live your life by honest and strong moral principles which include truthfulness, moral courage and openness in all your dealings.

Some years ago I knew a Mr Gibson who had been the personal assistant to Gordon Selfridge, the owner of the store of that name. He told me that he shared an office with him. One day the telephone rang and Mr Gibson was asked to answer it. “If it is for me, tell him I'm out” said Selfridge. Gibson took the call and handed the telephone to his boss. “It's for you” he said. Selfridge was annoyed and after finishing the call he said to Gibson “Why didn't you do what I told you and tell him I was out?” In telling the story afterwards Gibson used to say, “I cast my heart to the Lord and heard myself say to him 'I claim to live by Christian principles and if I can tell him a lie I can tell you a lie and am not going to do it.'” There was a long silence and then Selfridge said “You are quite right.” And always after that whenever there was an issue in the store Selfridge would ask, “What does Gibson say? Then that's what we'll do.”

Read Matthew 5:37

Integrity is a unity - a unit of one.

That is to say, you behave the same way in private when no one is watching as in public. Your life is not segmented. So why is a reputation for integrity so important and desirable?

Because truthfulness, generosity and humility are characteristics of God Himself. In this passage from Jesus' Sermon on the Mount, Jesus is reminding us that we are to be the sort of people who always tell the truth. We shouldn't need any extra sort of code or expression like “on my life” or “I swear to God, I am not lying” that would appear to give the impression that what we are saying now is more likely to be true than what we might say without such backing. When I was growing up the local auctioneer, a colourful character, had the reputation for total honesty – whenever possible! That isn't the standard that Jesus is looking for.

We are to be the sort of people who always tell the truth

Because whether we are conscious of it or not people watch what we say and do. If, over time, we gain a reputation for truthfulness, honesty, straight dealing, keeping our word even when it is difficult or costly, people who trusted us in comparatively small things will feel confident to trust us with much greater things.

Because whether you know it or not you are, or will become a role model for younger people who will begin to shape their own thinking and behaviour as they see how you model your life.

I am conscious that this concept of integrity seems to set an almost impossibly high standard in this day and age. How can we set about attaining to this standard? Is it possible? Let me end with some suggestions.

• Let's agree that integrity is important.
• Let's keep short accounts and seek to model our lives on that of Jesus, His love, His purity and honesty.
• Let's pray constantly to be filled with the Holy Spirit without whom we shall fall again and again but with whom we shall be being changed into His likeness.
• If we fail, let's acknowledge that we have, confess our failure to God and dare to believe that if we confess our sins, we are forgiven, and can start again.
• Let's have a small group of close friends that we can be open with and accountable to, and ask them to pray for us and help us – not to have to try all the time, but just to be. Honesty and integrity is the basis of all leadership and all Christian living.