Joshua 23:9
For the LORD hath driven out from before you great nations and strong: but as for you, no man hath been able to stand before you unto this day. For the LORD hath driven out from before you great nations and strong: but as for you, no man hath been able to stand before you unto this day.
The Lord drove out great and strong nations from before Israel and gave them victory, so that no one had been able to stand against them to that day. That success came from God Himself, who fought for them and was their source of strength. Joshua's review of that providence and past help was meant to awaken gratitude and to lead Israel to humility. That call to humility looked back on their past murmuring and neglect of God's revealed will. They were to trust Him and remain faithful to Him as they faced future conflicts.
The accompanying warning shows that God's faithfulness includes carrying out threatened judgment, for turning from Him would bring desolation. He is faithful both to His promises and to His threatened judgments. That lesson and warning apply to each individual person as well as to Israel as a whole. For individuals this includes the danger of idolatrous ties, intermarriage with idolaters, and approaching sin, which can lead to corruption and ruin.