The Purposes for Making God known: The purification and sanctification of the church

When we become Christians, we receive the Holy Spirit as a gift and
then the process of sanctification starts. We are positionally set apart
by God for holy purposes (Romans 1:1), but our natures still need to
change. We need to be purified. To belong to God means you belong
to the Holy One, the One without any moral corruption, without fault
or sin or unrighteousness. We, on the other hand, are not holy in
ourselves, we are defiled in our thinking, and we have corrupted
ourselves. We need constant cleansing and purification to have
communion with God and maintain fellowship with God. 
“Beloved, we are God’s children now, and what we will be has
not yet appeared; but we know that when he appears, we shall
be like him, because we shall see him as he is. And everyone
who thus hopes in him purifies himself as he is pure.” (1 John
3:2-3 ESV)
Everyone who is born again of the Spirit has a desire to be holy as
God is holy. However, we see unholiness and sin in ourselves daily. If
a person does not desire holiness in his or her life and has no desire
to be clean and pure, we can ask: has such a person really received
the Holy Spirit as a gift? How can a person receive the Holy Spirit and
not desire holiness? It does not make sense. How can a person who
has received a stomach not want to eat? How can a person who has
been given eyes not want to see beauty? How can a person who has
received a talent to play the piano, not develop it? God created us
for Himself and if we want to spend time with God, we must desire
to have His mind, His desires, dreams, purposes, righteousness and
His holiness. Therefore, the Bible tells us, everyone who hopes for
glory in heaven, purifies himself as God is pure. The church needs to
be purified, it needs more holiness, and it needs sanctification. 1
Thessalonians 4:3 tells us, “This is the will of God, your sanctification,
that you should abstain from sexual immorality.” Hebrews 12:14 tells
us that without holiness no one will see God. God called us to be holy
as He is holy (1 Peter 1:16). 

So, what does it mean to be pure and holy? Biblically, it means to be
separated from the world. It doesn’t mean one lives separated from
the world in the sense that you live alone on a mountain or an island
or in the woods for the rest of your life. Rather, it means that you
live and think and behave differently from unbelievers and people
that belong to the world. Jesus prayed for the church, asking not that
God would take them out of the world, but rather that He would
keep them from the evil one and that He would sanctify them
through His word (John 17:15-19). God wants us to live in the world
and make a difference in the world without being contaminated by
the world. We are like doctors living in a hospital. There are many
sick people in a hospital, and they have many kinds of diseases. Some
diseases are more serious than others; some are in the intensive
wards. Some are on the brink of dying and the doctors and nurses
are there to treat and diagnose and heal the patients with whatever
knowledge and medicine and equipment they have. In the same way,
Christians are in this sick world of sin. The people of the world are
dying; they have spiritual diseases, diseases such as pride, anxiety,
greed, lust, selfishness, vanity, hatred, jealousy, drunkenness,
addiction to substances, being lovers of self, etc. Some are on the
brink of destroying themselves. And we, the Christians, have
received the cure for our spiritual diseases; they are the blood of
Jesus and the word of God. We have the medicine; we have different
treatments for these diseases. We find them all in the word of God
and in the Person of Christ. The art of life is to maintain our spiritual
health within this sin-sick world! 
We know that it is only the blood of Jesus Christ that can cleanse us
from our sicknesses. Real Christians have experienced this cleansing,
this healing, when they confessed their sins and believed in the
power of the blood of Christ. They have experienced the healing
power of the gospel and it is incumbent on those who have
experienced this to prescribe this medicine to the spiritually sick and
to apply the word of God to the cancer of sin. 

“But if we walk in the light, as he is in the light, we have
fellowship with one another, and the blood of Jesus his Son
cleanses us from all sin. If we say we have no sin, we deceive
ourselves, and the truth is not in 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 1:7-9 ESV)
The purpose of the gospel and of evangelism is to be thoroughly
cleansed of our sins, and thoroughly purified from our
unrighteousness so that we can have communion with God from day
to day. Without sanctification taking place and the blood of Christ
being applied to our hearts through the Holy Spirit, we lose our
communion with God. We evangelize and make God known so
people can experience the satisfaction of sanctification, of being set
apart for God, of becoming purified, and more and more like Christ.
Jesus said to His disciples, “you are clean through the word that I
have spoken to you” (John 15:3). When we meditate on the word of
God day and night, when we read, and believe, and ponder, and
obey the word of God, we are washed, and purified. This then, is why
we evangelize, so that others can become pure and experience God,
and see God. 
Blessed are the pure in heart for they will see God (Matthew
5:8)
At the cross of Golgotha, the blood of Christ was shed for us, not
only to justify us (Romans 5:8), and to forgive us our sin; not only to
reconcile us to God, but to cleanse (1 John 1:7) and purify and
sanctify us (Hebrews 13:18): so that we maintain fellowship with
Christ! Let us draw near to God in humility and He will draw near to
us (James 4:5-8).