Yes we can overcome sin, but we still sin.
2 Corinthians 5:21
For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.
How can we become the righteousness of God? By repenting of our sinful ways. Do we still sin? Yes, because we are not 100% submitted to God. There are still areas in our lives where we sit on the throne, not God.
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Walk by the Spirit, and you will not fulfil the lusts of the flesh" (Galatians 5:17).
If we submit ourselves to God and walk according to the Spirit, we will not fulful the lusts of the flesh, or sin if you will.
James 4:7
Submit yourselves, then, to God. Resist the devil, and he will flee from you.
This is as plain as it gets. First, submit yourself to God. Then resist the devil (and anything pertaining to him, imo) and he will flee. I believe that submitting to God's authority will greatly improve our spiritual walk, reducing the amount of sin in our lives.
Is that what you are looking for?