This is only for people who believe the Bible to be God's word.
Littering is sinful because it violates two Biblical principles.
It is against the law. The Bible teaches us to obey the law of the land, as long as that law isn't conflicting with God's law (Daniel 3:1–30; Dan. 6:1–28; Acts 4:18–19; Acts 5:29; 1 Peter 2:13–17; Matthew 22:17–22; Romans 13:1–7; Titus 3:1). When man fails to be law abiding, he is failing to respect what God has said—he is also showing disrespect to the city, therefore he is sinning (1 John 3:4; 1 John 5:17; Psalm 119:158).
It is offensive. It is the right thing to keep the streets and neighborhoods free from trash, paper, cans, abandoned cars, dead animals, etc. If a person willfully dumpssuch filth onto clean streets because he is irresponsible and doesn't care about the hard work of others who are trying to keep the neighborhood nice, he is sinning because he has an attitude contrary to what the Bible teaches concerning neighborly conduct (Luke 6:31; Romans 12:17–18; Rom. 13:9–10; Philippians 2:3–5; Rom. 15:2–3; Acts 25:8, 11; James 3:2; Phil. 1:10; Acts 7:27; Rom. 14:13).