One of the first verse I ever memorized is this:
"I have hidden your word in my heart that I might not sin against you." Psalm 119:11 (NIV)
Have you ever noticed that Psalm 119, the longest Psalm, speaks continually about God's Word? It starts out in verse 1, "Blessed are they whose ways are blameless, who walk according to the law of the Lord." (NIV)
It ends with verse 176, "I have strayed like a lost sheep. Seek your servant, for I have not forgotten your commands." (NIV)
Obviously, the Psalmist (and God) believes that Scripture is important. It can keep us from sinning, as verse 11 says, but it cannot if we don't walk according to Scripture (verse 1)
Yes, we are saved by grace. We cannot follow the law perfectly because we have a sin nature that is passed down to each generation from Adam and Eve - true!
That's why we need a Savior - someone who followed the law to the letter - someone to take the punishment we deserve and then clothe us with holiness.
That person is Jesus. He, because He is God, was able to keep the law without breaking even one commandment. He was, and is, perfect. He was slaughtered - on a cross - and He rose from the dead. He took the punishment for sin and clothed us with His righteousness and holiness.
If you haven't repented - turned away from the sin in your heart and in your life- you're still guilty of breaking the law. You'll take the punishment due you - eternal death.
God requires perfection. He requires holiness. He requires that His people "walk according to the law of the Lord."
You can't do it without Jesus.