The Greek epiteleō (G2005) means to bring something to its intended completion — to carry through, finish, or accomplish fully. Paul uses it in Philippians 1:6: 'He who began a good work in you will carry it on to completion (epiteleō) until the day of Christ Jesus.' This is one of the NT's most comforting assurances: God finishes what He starts. In 2 Corinthians 8:6, Paul urges the Corinthians to bring their charitable collection to completion (epiteleō).
Epiteleō in Philippians 1:6 is the basis for the doctrine of the perseverance of the saints — not that believers persist by their own power but that God 'carries through to completion' His redemptive work in them. The prefix epi- intensifies the completion: it is not merely 'to finish' but 'to bring to its appointed fullness.' The God who began the good work of new creation in believers will not abandon it halfway. The parable of the Tower Builder (Luke 14:28-30) warns against beginning without finishing; God never fails to complete what He designs.