Col 2:9-10 says, 9 For in him the whole fullness of deity dwells bodily, 10 and you have been filled in him, who is the head of all rule and authority.
'The whole fullness' - plḗrōma, (play'-ro-mah) in Greek means abundance or completion.
Our salvation comes with fullness. God has given us a keeping gift. It requires owning, maintaining, and protecting. For example if someone gave you a gift that you desired you would do your best to take care of that gift you would claim your ownership. you would protect it making sure its not destroyed or used irresponsibly. You would also make sure it's been maintained either by you playing with it or utilizing it or even keeping it clean. When this happens you get the fullness of the gift. You get everything out of what the gift has to offer.
Essentially, the gift of salvation does the same thing. When you receive the gift, own it, maintain it, and protect it you are able to reap the fruits of what God has to offer. You get to claim rule and authority.