Why is the concept of being filled in Christ important for Christians?

The importance of being filled in Christ lies in the assurance it provides to believers about their salvation. As mentioned in Colossians 1:9, the Apostle Paul prayed for them to be filled with the knowledge of God's will. This filling indicates that all spiritual sustenance is provided through Christ, ensuring that believers are not lacking in grace, love, or knowledge of God. As believers are rooted in Christ and are being built up in Him, they can confidently navigate the challenges of life, knowing that their completeness rests solely in Him.