JOEL - You are right, no one can enter the highest level of the Celestial Kingdom and be in the presence of God there if they have any sins or flaws or have not been perfected. But we don't have to do it all in this life time. Who knows how long we will be in the spirit world, and then after our resurrection and the thousand years during the Millennium and after that before we are judged and assigned a level of glory. We have all that time to work on it. And I certainly can't do it myself. It is only by and through the grace of God that we can be exalted. But the scriptures tell me that there are things that I must do to become the kind of person that can be saved. For example:

"And, behold, one came and said unto him, Good Master, what good thing shall I do, that I may have eternal life?
And he said unto him, Why callest thou me good? there is none good but one, that is, God: but if thou wilt enter into life, keep the commandments.
He saith unto him, Which? Jesus said, Thou shalt do no murder, Thou shalt not commit adultery, Thou shalt not steal, Thou shalt not bear false witness,
Honour thy father and thy mother: and, Thou shalt love thy neighbour as thyself.
The young man saith unto him, All these things have I kept from my youth up: what lack I yet?
Jesus said unto him, If thou wilt be perfect, go and sell that thou hast, and give to the poor, and thou shalt have treasure in heaven: and come and follow me." (Matt 19:16-21)

So, among other things, we must keep all the commandments and give to the poor in order to obtain eternal life. But it is not just the doing of these things that saves us, it is what we become(perfect) by doing these things.
Notice that Jesus said to the man "if thou wilt be perfect" and then told the man what he personally could do to perfect himself. So according to Jesus it is possible for us to do something that will help effect our salvation and not only rely on the perfection or worthiness of Jesus to save us.