What is being blameless?

1 Cor. 1:7, “Who shall also confirm (establish) you unto the end, [that ye may be] blameless in the day of our Lord Jesus Christ.”

The Greek word means ” that cannot be called into to account, unreproveable, unaccused, blameless.”

How does this take effect? What do I need to do to make it happen?

Answer: nothing.

It is the impartation of the knowledge and understanding by grace that sin cannot be held to my account ever again by the revelation of Christ and His complete work on the cross.

Col. 1:9, “(We) do not cease to pray for you, and to desire that ye might be filled with the knowledge of his will in all wisdom and spiritual understanding;”