Lets look at something here.When a child does something wrong,they are still the child of their parent(s),that does not change regardless of what they do.The child can choose to do wrong,the child can say that their parent(s) are no longer such but the fact is,they are the child of the parent(s) and they cant change that.
When a person becomes a child of God,they become heirs and joint heirs with Jesus Christ.They are Gods children and will stay Gods children regardless of what they do.This doesnt give the child a free pass to do what they want because they will still have to pay for their wrong but they remain saved.
A person can not keep themselves,a sin is a sin and any sin would cause the person to be out of union with Christ and therefore they would be lost.In this scenario,few if any would go to Heaven because many would not have the chance to renew the union with Jesus before their death.
If a person is going to live by this way of thinking,they most likely will die and miss Heaven,Why?
Because the Bible says that he that knoweth to do good and doesnt,it is sin.
James 4:17
Therefore to him that knoweth to do good, and doeth it not, to him it is sin.
This is something that most of us fail to do every day and if you believe that we keep ourselves,you would have to be lost.
Salvation is an unearned Gift from God,we dont deserve it,wo dont earn it,we dont get it by works and we dont keep it by doing these things either.We are sealed and kept by the Holy Spirit.
Heb.6:4-6
For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
6:5
And have tasted the good word of God, and the powers of the world to come,
6:6
If they shall fall away, to renew them again unto repentance
A person can be and MUST be sure of their salvation in this world,if not;
1 Corinthians 15:19
If in this life only we have hope in Christ, we are of all men most miserable.
If a person isnt sure of their Salvation in this life,it will be to late in the next life,it is a must to have this settled before you leave this world and you can be sure by accepting the gift of Salvation from God by accepting His only beggoten Son,Jesus Chrsit as your personal Lord and Savior.
I cant say who is or isnt Saved but if a person thinks that that cant know for sure in this life,they are wrong.A person can know if they are saved and the Bible teaches that they can.
1 John 3:14
We know that we have passed from death unto life, because we love the brethren.
8:16
The Spirit itself beareth witness with our spirit, that we are the children of God:
8:17
And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.