How do we know that God's work in believers is true?

The assurance given in Philippians 1:6 declares that "He who began a good work in you will bring it to completion at the day of Jesus Christ." This verse confirms the certainty of God's promise regarding His work in the lives of believers. The gradual process of sanctification reflects the reality of God's faithful engagement in our growth through the Holy Spirit. Just as jewels may take time to be perfected, believers are being gradually made fit for heaven, assured that God will faithfully navigate them through trials and transformations toward their final glorification. This underscores the permanence and reliability of God's redemptive work.