Start Small
How do you know that somebody can be trusted? Usually, you look to see if there is any evidence of trustworthiness. Those who have been reliable, honest, effective and productive in other matters may also be able to manage your business. That is the basis of business references; if the applicant for your job has a glowing testimonial from a previous employer, then you may be encouraged to appoint the person.
Jesus makes the same point. Honesty breeds honesty, and dishonesty is likely to be repeated. The way somebody handles money is a good indicator of spiritual trustworthiness (Luke 19:17); in the same way that the ability to manage a family is a good indicator of suitability to be a church leader (1 Timothy 3:5). Those who cannot be trusted with money are unsuitable gospel messengers (1 Timothy 6:9-10).
God uses worldly wealth as a test to see how well God can trust His children with handling truth and the glorious things of lasting value. When Solomon had the opportunity to ask God for wealth, he asked God for wisdom to handle his existing responsibilities well (1 Kings 3:7-9). Jesus was training His apostles to take the precious truths of salvation into the world and be instrumental in planting churches to the honour and glory of the Lord Jesus. He had selected the Twelve and was now testing them (Luke 10:1-7). One, Judas Iscariot, would fail the test. He was known to be a thief (John 12:6) and his lust for money even led him to betray his Master for money (Matthew 26:14-16).
We need to see the practical activities of everyday life at home and work as being divine tests to train and equip those whose character is faithful to God. We must not divide our lives into sacred and secular compartments because what we really are will show through. If that thought is horrifying, there is still time to repent and choose to replace old habits with new ones. It may take time to learn a different way, but, if we do not, there is little credit to our discipleship.