The people of Israel may have been following God, but it doesn't mean they were following Him with their hearts and minds. We must make sure that we aren't just following God in actions without surrendering ourselves. Paul gives specific instances of things that Israel didn't watch out for that led them astray, warning Corinth (and us) of things we need to watch out for. He includes references to idolatry, sexual immorality, testing God, and grumbling. Paul brings up these examples so we can watch out for the ways the enemy is trying to lead us astray from worshipping God.