Of course I need Christ to be able to live a life without sin. I cannot be sin-free unless I abide in Him (1 John 3:6).
All have sinned and "come short" of the glory of God.
The words in quotes are in the present passive indicative...and they indicate that it is the person who is not active in pursuing Christ is presently coming short of the glory of God.
But if you are pursuing Christ, the present active indicative would make the following true of you.
1Th 5:23, And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.
1Th 5:24, Faithful is he that calleth you, who also will do it.
Heb 10:14, For by one offering he hath perfected for ever them that are sanctified.
1Jo 3:9, Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God.
the last of those verses may in fact be hypoerbole; but if it is, it is John exaggerating to make a point.
What point?
That those who are born again have made a 180-degree turn away from sin, death, hell, and satan, towards righteousness, life, heaven, and God. So, they are walking in a new direction; so that the following is true of them.
Pro 4:18, But the path of the just is as the shining light, that shineth more and more unto the perfect day.
Notice it does not say, "
If we say that we do no sin, we deceive ourselves, and the truth is not in us."
Read 1 John 1:8 again.
It is speaking of indwelling sin.
The element of sin within us can be rendered dead (Romans 6:6, Galatians 5:24, Romans 7:8) so that it no longer has any say over our behaviour (Romans 6:14).
Thus, it should be clear that 1 John 3:5-9 is speaking of practical behaviour.
Easy...1 John 1:7. the Greek word there, for "cleanseth" is in the aorist present perfect indicative;
And therefore it can be translated as "continually cleanseth".
And it is the blood of Christ that cleanseth us from all sin.