Shane Idleman emphasizes the theme of God as the avenger of His people in his sermon based on Psalms 35, addressing the current societal challenges and moral decline. He highlights the importance of prayer and trusting in God's sovereignty amidst rising persecution and confusion in the nation. Idleman encourages believers to maintain a righteous attitude, reminding them that while they may feel frustrated, God is aware of their struggles and will ultimately vindicate them. He stresses the need for humility and joy in the Lord, urging the congregation to focus on God's goodness and to speak of His righteousness daily. The sermon concludes with a call to action for believers to rise above negativity and to trust in God's plan for justice and restoration.