The elect are sanctified only by the sufferings and death of Christ on the cross

"The Apostle adds for the purpose of more clearly explaining what the will of God referred to in the prophetic oracle meant, - ver. 10- 'By the which will' - according to which benignant good pleasure of God - 'we are sanctified, through the offering of the body of Jesus Christ once for all.' The will of God was completely fulfilled in Christ's offering His body once for all for the sanctification of His people. The sanctification of Christ's people does not mean exclusively or primarily the making them inherently holy; - it means the expiation of their sins, leading to the remission of their sins, the quieting of the conscience, the purifying of the heart, and thus to the consecrating of them to God as 'a peculiar people.' This was done by the one offering of the body of Christ; i.e., by what He did and suffered in their nature, and in their room. In this way the will of God was accomplished. He was glorified in man's salvation. Justice was satisfied, and mercy had free course. This was the work the law could not do, but which God has done by the incarnation and sacrifice of His Son." - John Brown, Epistle to the Hebrews, pg. 443