Their end is destruction, their god is their belly, and they glory in their shame, with minds set on earthly things. (ESV)
There is only one way to be made right with God. It is by accepting the free offer of God's grace through Jesus Christ. It is sad that there are people who spend years in church and reject that offer. They insist on a salvation outside of the cross of Christ, and depend instead on their own works. In the church at Philippi it was the Judaizers. They insisted on keeping of the law for salvation.
Paul has a warning of severe judgment for those who reject the cross of Christ. He says that their end is destruction. Consider those whom you spend time with at your local church. Some of them may have accomplished many things. They may have done many good deeds. If they have rejected the Gospel of Jesus Christ they will spend eternity in hell. That is a very sad reality.
For the Judaizers in Philippi their works focused on keeping the Old Testament Law with all of the ceremonies and rituals. Paul says that instead of worshiping God their god is their belly. This likely refers to all of the dietary restrictions and feasts that were all part of the ceremonial law. They embraced ritual while discarding true righteousness.
Those who do not accept Christ, giving him glory for what he has done for them end up glorying in their own efforts. This brings shame because none of us are holy. None of us can provide our own righteousness. What a tragic thing it is to spend all of your life wasting your efforts, while rejecting the free offer of Christ.
Ask God to help you to reach out to those who have not yet accepted salvation by grace. They must not be allowed to influence the church, but they also need to be loved to the Savior.