The meaning of sanctification, in its original Hebraic context
The modern definition of sanctification is to be holy, pure, perfect, pious, made righteous, and walking before Him sinless. This understanding generally deals with "self" and moral character and is derived from a Greek → Latin → English (Western) understanding. While this definition seems right and natural, and fits in some contexts, it is one-dimensional and falls short of fully conveying sanctify (SDQ / sdq / kadosh).
To undersand any word in the New Covenant, it is best to understand how it was first used in Hebrew (Tanakh). The dictionary for the New Covenant is the Old Covenant (Tanakh). Hebrew, in its original form, was pictoral and gives us the basis by which we can understand Hebrew words and letters.1 The English word sanctify/holy comes from SDQ (read right to left).
|Q||Sun on the horizon
Back of the head
|Gathering (sun 'gathers' its light on the horizon)
Behind (due to circular time)
|D||Tent door||Opening, pathway|
So, we can see SDQ (sdq / QDSh / kadosh) means 'to leave behind (horizon/back) and separate (teeth) from/unto (door)' a distinct purpose. Unlike the modern western understanding, to be set-apart includes both from and unto just as a door can give you both functions. Sanctification simply means; to set someone or something apart for a distinct purpose.
Law of first mention
We know that sanctification means 'to set-apart' from the pictures/letters in the word, but also from the first time it is used in the Tanakh2. The 'law of first mention' states that the first time a word is used in the Scriptures, it almost always carries that same primary definition throughout. The first time we see sanctify used in the Scriptures is in relation to the seventh-day (Sabbath). Elohim set the seventh-day apart from the prior six days, making it unique and distinct from the first six mundane days.
Genesis 2:1-3, And the heavens and the earth are completed, and all their host; and God completeth by the seventh day His work which He hath made, and ceaseth by the seventh day from all His work which He hath made. And God blesseth the seventh day, and sanctifieth it (set it apart), for in it He hath ceased from all His work which God had prepared for making.
With this background in mind, we can understand why tools, land, animals, garments, time, and even a kiss can be 'sanctified (set-apart)'. A tool cannot be holy (sanctified) in and of itself, but it can be set-apart for a specific use. This definition holds true throughout Scripture. So, in reitteration, to be sanctified does not mean sin-less, or the process to living sin-less. Living sin-less can only be a fruit of being set-apart unto Yahweh.
Set-apart chosen-ones (elect)
Paul calls YAHWEH's people set-apart (sanctified):
Colossians 3:12, Therefore, as chosen ones of Elohim, set-apart and beloved, put on compassion, kindness, humbleness of mind, meekness, patience, bearing with one another, and forgiving each other if anyone has a complaint against another, indeed, as Messiah forgave you so also should you.
In this usage we can see that sanctification (set-apartness) was not the goal, but that God's chosen-ones (Israel) were already set-apart to Him. Here we can see that because YAHWEH has displayed compassion to His chosen-ones, we too are to put on compassion... and should forgive one another. Putting on meekness, humbleness, and patience does not make one set-apart (sanctified), but is how His elect is expected to walk in Him.
1 Ancient and Paleo-Hebrew was used pre-Moses till about 70ad, although we see it beginning to fade at the beginning of the Second Temple period when the modern 'Hebrew square script' was likely adapted. Biblical Hebrew, as we now call it, was merely an equal exchange from 22 pictures to 22 letters. Biblical Hebrew (letters) started being used during the time of Ezra and in large part is comparible to modern Hebrew used today.