Although there were many people who wanted to hear Jesus and see His miracles, the twelve apprentice-apostles were His first ministry priority.  They would soon have the task of leading the fast-growing church which would eventually spread to every country.  So, they needed to be clear about all the essentials so that they could help many others to believe in Jesus and follow Him.   

After His encounter with the Pharisees (Luke 11:37-54) the disciples realised that there was a very sharp contrast between Jesus and the other spiritual leaders.  Jesus had integrity.  He did what He said and was never different in private than in public.  That sort of integrity contrasted with the hypocrisy (the word means 'stage acting') of the Pharisees (Matthew 6:1-18) who made a lifestyle out of pretending to be holy but being quite different in their hearts.  

Hypocrisy easily spreads and could contaminate all the disciples (as it did in Judas Iscariot), and from them corrupt the church.  The idea of hypocrisy being like yeast was potent imagery to the Jewish mind.  The tiny micro-organism of yeast which made bread rise would also make bread go stale and mouldy - which was why the Israelites leaving Egypt with Moses took unleavened bread (Exodus 12:34).  Yeast multiplies very rapidly and once it is present it is almost impossible to eliminate … hence the warning to beware of allowing any hypocrisy into their lives.  Jesus said that if the apostles started acting, they would slander the transforming power of Jesus, and the church would start on very shaky foundations because hypocrisy will always be exposed for what it is, a sham.

Alas, hypocrisy is not far from any of us.  We are surrounded by it and almost believe it is a normal way to live in the workplace or the church.  It is infectious.  It is an acted out play of lies which are built on earlier untruths, until the point is reached where nothing is credible any more.  Hypocrisy will wreak havoc in any church, diverting ministries and destroying reputations.  Now, as much as when Jesus spoke, we need a fresh commitment to integrity for all Christian individuals and churches.  The truth is that the gospel is truly amazing in its outpouring of grace, the Holy Spirit is astonishingly powerful and God's love is the ultimate consolation and motivation. Why sell the gospel short by acting out what is not real, when the reality is life transforming?