Holy and without blame an impossible task for the best of us but then again if your in Christ that is exactly what God declares you to be.

Eph 1:4  Even as [in His love] He chose us [actually picked us out for Himself as His own] in Christ before the foundation of the world, that we should be holy (consecrated and set apart for Him) and blameless in His sight, even above reproach, before Him in love.

God has chosen you in Christ, He looks at Jesus and because of His perfect sacrifice, which was the fulfillment of all that the law required blameless and sinless being a perfect man who is blameless, God accepts Jesus sacrifice for the sin of all the world gaining you access into the very presence of God the Father for you, which you had lost in the garden of Eden when Adam and Eve disobeyed the command of God not to eat from the tree of the knowledge of good and evil. Änd you He made alive who were dead in trespasses and sin” (Epesians 2:1) Because of Jesus sacrifice at Calvary, God now looks at you the same way He looks at His son, a perfect son, blameless, faultless, with no sin, no guilt, in fact He pronounces to you, your Holy in my sight, blameless and above reproach. 

God sees only His son when He sees us, that is why we can be holy and blameless, and without reproach . Outside of Christ, in our own human state which is inherently evil, to be  Holy and blameless is an impossible state to be in, all have sinned.Now that  you have handed your life over to Christ, for when you do that, Jesus lives in you and makes all that was wrong with you right, according to God’s word.   You don’t focus on your short comings, your sins, your problems, you look to Jesus who has hidden you in Him, He in you and you in Him, He is your hiding place, your Redeemer, your shelter, He  now is responsible for your life your part is to believe in His finished work that was done at Calvary.  Because He lives you will  live also, He has made you alive in Christ.