It's human nature to look down upon those who are different or perceived to be "less capable" than ourselves. In the First Century, the blossoming Christian church was a great melting pot of people from very different backgrounds including diverse cultures, socioeconomic strata, and most importantly varying levels of Christian knowledge and faith. Many of the new converts were once orthodox Jewish believers. This melting pot caused great rifts in the church between Gentiles who shunned the Mosaic laws (primarily the food laws and belief in honoring the Sabbath) and devout Jews who staunchly believed in upholding their cultural and religious laws. Paul makes very clear that many issues in the Christian church are matters of personal belief and opinion. It's important to honor God in our own way, but just as importantly, we can't let our own personal opinions and beliefs cause us to judge other Christians.