Read 1 Thessalonians 2:9-12

You yourselves are our witnesses—and so is God—that we were devout and honest and faultless toward all of you believers. – 1 Thessalonians 2:10 (NLT)

Along with pure motives, we must make every effort to see that our way of living squares with what we say we believe. People will believe what they see we are. If that contradicts what we say, our witness is disregarded. If it reinforces what we say, they will be more likely to respond positively as the Holy Spirit speaks to them.