Not everyone who preaches the gospel is sincere.  Paul informed the brethren at Philippi that he was aware of those who had the wrong motive for preaching the gospel.

Philippians 1:15-17 (ESV)
¹⁵  Some indeed preach Christ from envy and rivalry, but others from good will. ¹⁶  The latter do it out of love, knowing that I am put here for the defense of the gospel. ¹⁷  The former proclaim Christ out of selfish ambition, not sincerely but thinking to afflict me in my imprisonment.

These were not the last ones to preach the gospel for the wrong reasons.  Think about the many TV evangelists today who preach the gospel for shameful or dishonest gain, or, as the KJV says, for filthy lucre.  I could give details of Jesse Duplantis coaxing his congregants into buying him a 54 million dollar plane.  Robert Tilton is another example.  His prayer request and donation letters (where the donations ended up in his bank account, and the prayer requests in the dumpster, as discovered by ABC investigators) show where his heart was.   There are many other TV personalities, posing as evangelists, but whose real aim is to get rich (Peter Popoff, Jim Bakker, Paula White, Earnest Angley, etc.).

TV evangelists are not the only ones who preach the gospel insincerely.  Paul not only told the saints at Philippi about those who were preaching with wrong motives, he also warned the brethren in Ephesus that some would come their way.

Acts 20:29-30 (ESV)
²⁹  I know that after my departure fierce wolves will come in among you, not sparing the flock; ³⁰  and from among your own selves will arise men speaking twisted things, to draw away the disciples after them.

In this case, the motive is not for dishonest gain, but to draw away disciples.  Some preachers preach just to gain a large following, and to be popular with people.  That kind of motive is not only sinful within itself, it leads to a compromise of the faith and a watered-down version of the gospel being preached.

While there are plenty of examples of the gospel being preached insincerely, our first concern should be with ourselves.  Why do you preach the gospel to others?  Why do I?  We should follow the good examples that Paul referenced to the Philippians, that is, those who preach from good will and out of love (Philippians 1:15-16).

Love is always a good motive when doing something, especially something as important as preaching the gospel.  We should preach the gospel because we have a real passion to win souls for Christ, and that passion should be the result of a sincere love that we possess for others.  Paul is a good example of this.  He was willing to sacrifice his liberties in Christ just so that he might save some (1 Corinthians 9:19-22).  His love for the souls of men was obvious, and so was his love for Christ (2 Corinthians 5:14), which is another great motive for preaching the gospel.  Our aim in preaching the gospel should be to win souls and glorify God.

It is only when we have the right motives, when we preach, that the gospel is advanced correctly.  When one’s motives are insincere, he will quit preaching the gospel as soon as he realizes that he is not going to get want he wants.  If, on the other hand, our aim is to win souls and glorify God, we will preach the gospel until the Lord returns, diligently advancing His cause.  

As you wind down for the night, think about these things.