Read 1 Thessalonians 2:4-8

Our purpose is to please God, not people. He alone examines the motives of our hearts.
1 Thessalonians 2:4b (NLT)

Not-yet-believers will naturally be suspicious of our motives when we present the gospel, for we are calling them to change. Therefore we must continually examine our motives to make sure we are really living in obedience to God, not relying on our salesmanship to persuade people to turn to Christ. Our purpose must always be to please God, and leave the results to Him.