Yet Paul in the very same Hebrews ten that you quoted says:
24 And let us consider one another to provoke unto love and to good works:
25 Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching.
26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
27 But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
28 He that despised Moses’ law died without mercy under two or three witnesses:
29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
Paul contradicts you here as he is saying that the saints need to encourage each other to love and to do good works (i.e. not to sin). What is the point of encouraging each other to do good if we are already saved? Are you just doing God a favour by doing good? Is God somehow indebted to you so that he needs to allow you to do whatever you want and still needs to save you?
When Peter saw Jesus walking on water he asked him if he could also walk with him. Jesus gave him the go ahead. But when he saw the mighty waves he became afraid and stopped focusing on the Saviour. At that moment he began to drown. Christ rescued him and asked, "O thou of little faith, wherefore didst though doubt".
The work of every Christian who wishes to inherit eternal life is keep their eyes fixed on the Saviour. There is a lovely scripture about this in D&C 88:67:
And if your eye be single to my glory, your whole bodies shall be filled with light, and there shall be no darkness in you; and that body which is filled with light comprehendeth all things.
Jesus is the light and when we are focused on him our whole bodies are filled with light and there is no darkness (or sin) in us. Therefore if you are in the habit of sinning "a little" then it is certain that your whole body is not filled with light and there is still some darkness in you. And if your whole body is not filled with light then it can only be because you have stopped focusing on the Saviour. Remember the Saviour said his disciples shall be known by their love. And Paul said love thinketh no evil. And if you don't think any evil then you cannot do any evil: not even "a little".
And our sins are our fault. God has all power to deliver us from the devil. But he will not deliver us against our will. If we want to sin it is our choice and he will not stop us.