The word “sanctify” is one of those “Bible” words that only the religiously-inclined seem to know (but might not actually understand what it means). Google defines the word so: “to set apart as or declare holy; consecrate; purify, free from sin, make clean.”
Our name for God this week is “YHWH-M’Keddesh”. This name means “The Lord who sanctifies”. God sanctifies. He is one who sets apart and IS set apart. He is a holy God. He is so wondrously holy, that whenever His holiness is mentioned in the Bible it is often said “Holy, holy, holy is the Lord”. Three times in the Bible represents perfectness. God is perfectly holy.
A God who is holy, set apart from evil requires those who worship Him to also to be holy and set apart from evil.
“Consecrate yourselves, therefore, and be holy, for I am the Lord your God. Keep my statutes and do them; I am the Lord who sanctifies you.” – Lev. 20:7-8 ESV.
“For this is the will of God, your sanctification” – 1 Thes. 4:3 ESV
Unfortunately, our sinful nature tends to make that impossible. We cannot make ourselves holy. That is why we have a need for a God who will do it for us, a God who will cleanse us.
“If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness” – 1 John 1:9 ESV
It makes sense that the only one who can cleanse us from sin is the only One who is free from sin Himself. So, in the words of Paul:
“Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ.” – 1 Thes. 5:23 ESV