This passage below is from the King James Version (ekjv.org).  

Remarks from the Berean Fellowship follow the passage below.

[1] Paul, and Silvanus, and Timotheus, unto the church of the Thessalonians which is in God the Father and in the Lord Jesus Christ: Grace be unto you, and peace, from God our Father, and the Lord Jesus Christ.
[2] We give thanks to God always for you all, making mention of you in our prayers;
[3] Remembering without ceasing your work of faith, and labour of love, and patience of hope in our Lord Jesus Christ, in the sight of God and our Father;
[4] Knowing, brethren beloved, your election of God.
[5] For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake.
[6] And ye became followers of us, and of the Lord, having received the word in much affliction, with joy of the Holy Ghost:
[7] So that ye were ensamples to all that believe in Macedonia and Achaia.
[8] For from you sounded out the word of the Lord not only in Macedonia and Achaia, but also in every place your faith to God-ward is spread abroad; so that we need not to speak any thing.
[9] For they themselves shew of us what manner of entering in we had unto you, and how ye turned to God from idols to serve the living and true God;
[10] And to wait for his Son from heaven, whom he raised from the dead, even Jesus, which delivered us from the wrath to come.

Turning to God from Idols

God established His people (israel) in the midst of the nations, and all of the nations were idolatrous. They were all largely worshiping false gods. The images that they would make and bow to and give sacrifices for were representatives of fallen angels and their offspring that they worshipped. These fallen beings were previously members of the divine council and they were granted regions on earth that they were to watch over. This is why they are referred to as watchers. They sinned through abandoning their heavenly estate and took upon the form of men and took wives from men on the earth.

So there is a truth behind the legends of the gods and the pantheons in the world. The offspring of their unholy union resulted in creatures that were half angel (god) and half man. It seems the first iteration of these creatures grew to an enormous size. They're human counterparts destroyed one another as well as consuming the earth along with the men that god created to dwell on the earth. This is the overarching reason for god destroying the earth through the worldwide flood. When these beings that were half man and half god died, their spirits could not return to god, because they were not god's creation. Their spirits were bound to the earth and they became what is commonly called a demon or a devil.

• Read Genesis 6 and the book of Enoch 1

The pagans worshiped many of the fallen angels (gods) as well as the demigods (half man, half god). This pagan type worship even endures today, but it is largely secretive.

One can see iterations of these false deities in modern sculptures all over the world and in most cities of the united states. Paganism endures.

Idolatry: Then and Now

Why did they worship false gods?  

Because they got stuff from them. If they honored the false deities the false deities would do things on their behalf. Of course the idol itself was nothing but wood or stone or metal, but the spirit that it represented existed in the spiritual reality and could perform on the behalf of those that worshipped them.

The people of Israel were charged by the Most High God to worship only Him. The false gods, or the "little g" gods, were no match for the ONE living and true, Most High God. He also commanded his people to never make an image to represent Him. The apostate Roman Catholic religion is an idolatrous, multi-theistic religion.

Pagan idolatry

Pagan worshipers offered all sorts of sacrifices to their false deities including human blood sacrifices. It is sick and it endures even to this day. They had physical idols that represented the spiritual entities that they served.

Present idolatry

The pagans worshiped the false gods in order to get stuff from them (materialism). The moderns try to fill their lives with stuff (materialism), believing that this will yield fulfillment to them. Three times in the New Testament we are told that covetousness IS idolatry. In much of the modern world, the "normals" of the society need to turn from covetousness or materialism to God. This is the modern day application.

 Col 3:5

Mortify therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry: