James 1:8 is talking about faith in what we pray for. I suppose that calling it inner unity is a good description. We all need peace, not as the world gives, but as Jesus gives—inner peace, which as you say is inner unity. But the purpose of God’s work does not stop with inner unity. God calls us to use our talents, including our peace, for His kingdom. Jesus told the parable of the talents in Matthew 25:14–30. The one who kept his talent to himself, did not invest it in the kingdom, was rebuked by the master. Unity is the result of loving as Christ calls us to do. I do not always feel love, say as an example for my family, but my love for them has not changed. Love and unity are more than feelings.