The promise is that the gift of eternal salvation is ours through the communion of the One Holy Catholic and Apostolic Church; yet to claim it we have to read, and, more importantly, live, the rest of the scripture and not pluck it apart verse by verse.
"12 ... With fear and trembling work out your salvation. 13 For it is God who worketh in you, both to will and to accomplish, according to his good will. 14 And do ye all things without murmurings and hesitations; 15 That you may be blameless, and sincere children of God, without reproof, in the midst of a crooked and perverse generation; among whom you shine as lights in the world." (Philippians 2).
"The promise"
It isn't a promise, it is a statement of fact, a completed action without regard to the past, present or future. When you trusted you were sealed, period. Nothing else is necessary for justification and regeneration. Everything else is working out what one is, saved to the utter most. Now one can get on with the business of working out that salvation with the new life that has been given without having to worry about whether the redemption took or having confessed enough to the professional.