After Cane murdered his brother and God asked him where Able was, Cane flippantly replied, "Am I my brother's keeper?"(Genesis 4:9). God responded, "the voice of your brother's blood cries out to me from the ground" (Genesis 1:10).
A popular American saying is, "I don't care what other people think." In some context this may be important, such as following Christ regardless of persecution. But to have the saying as a mantra for our lives violates biblical teaching.
God holds us accountable for our interactions with others. Jesus said, "whoever is angry with his brother without cause is in danger of judgement" (Matthew 5:25). Paul dedicates the entire fourteenth chapter of Romans to our responsibility to our brothers.
Paul, Silvanus and Timothy knew their behavior influenced people's perceptions about what they had to share. Our character dictates the quality our influence (1 Thessalonians 1:5).
