[Colossians 1:23 ESV] 23 if indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that you heard, which has been proclaimed in all creation under heaven, and of which I, Paul, became a minister.
The security of the believer is the perseverance of the believer. If the Holy Spirit indwells us with His saving work we will continue and abide in Christ Jesus throughout the journey of life (John 8:31, 15:5). God is faithful to those who believe and place their whole-hearted trust in the Savior's death, burial, and resurrection (Hebrews 10:23). In fact He remains faithful even when aren't (2 Timothy 2:13). This is a different state than those who have "tasted" and "partaken" of the Holy Spirit for a temporary experience and then fall away (Hebrews 6:4-6). These are the seeds who go into shallow-rocky soil and never are truly saved by God's grace (Matthew 13:5-6, 20-21). They only receive it with joy for a little while, but are not stable and steadfast in their devotion to the Lord and His gospel.
This plan of salvation has been "proclaimed" in various ways Paul says here "in all creation under heaven." God's plan is not hidden. He wants all to know Him and accept Him as Lord and Savior. Paul, because he knows the Lord in relationship, recognizes that because of the gift he received from Jesus he is now a minister, a servant, of the Living God. He spreads the good news and helps people come to the Savior. We should be about this same type of business if we have received Christ.
*Life Point* Don't ever shift from the hope of the gospel that you have heard. Be stable and steadfast in your relationship with Christ, the Savior.