The passage begins talking about not arguing with a “weak” believer. In this context a weak believer is one who hasn’t fully grasped their freedom in Christ and is bothered by choices and preferences of others that don’t matter in the long run. A “strong” believer is one that can exercise their freedom in Christ without burdening others with their own personal feelings. Too often Christians get weighed down, and in turn weight down others, with things that are not important. We focus on the little things, often matters of personal preference, and let them overtake the big things where we agree. This is an issue of spiritual maturity – being able to appreciate that two people who love God can see an issue differently and both still be loving God.