Joshua’s life exemplifies obedience to God, leading to victory and peace, unlike the pride and greed that result from self-reliance. In his exhortations, Joshua calls Israel to serve the Lord with sincerity, meaning wholehearted commitment, avoiding compromise, and obeying God’s commands fully. Sincerity in both the Old and New Testaments involves authenticity, humility, and a sincere pursuit of holiness, shaped by the Holy Spirit.