A big theme from Joshua 12 is unity. The lands to the east and west of the Jordan are mentioned. Joshua and Moses are mentioned together with all the Israelites. The Lord is uniting his people together.

The unity of God’s people is something that must be guarded. It is a unity in faith (Ephesians 4:4–6) that must be maintained with effort (Ephesians 4:3). We cannot simply assume that we will stay united as a church; we need to work hard at maintaining unity.

Since the church is a gathering of believers from all nations (Psalm 87:1–7; Acts 2:1–47; Revelation 7:1–17), there will always be lots of different things that divide us. We won’t all be from the same ethnic group, we won’t all be rich, and we won’t all have the same level of education. We must be careful that we do not consider some believers to be more significant than others. This was a challenge in the early church where they treated people differently based on their economic status (James 2:1–9), and some of the Jews did not want to associate with Gentiles (e.g., Galatians 2:11–21). Likewise today, we can sometimes exclude people who don’t share our hobbies or interests and treat those who have sinned as if they are worse than us (e.g., people who are divorced).

We need to be tolerant in God’s church when it comes to opinions, cultures, and other secondary differences, but we must be intolerant when it comes to doctrine. The church is meant to be united in faith around the teaching of the apostles (Jude 1:3). There can be no room in our churches for people to teach a different doctrine from what was taught by the apostles and is found in the Scriptures (Galatians 1:6–9). This is why it is so important for our churches to know what the Bible teaches, and for preachers, elders, and members to publicly testify their agreement with clear statements of faith such as the Ecumenical Creeds (Apostles' Creed, Nicene Creed, Athanasian Creed) and the Reformed Confessions (Belgic Confession, Heidelberg Catechism, Canons of Dort).