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Before going directly to the type of fidelity that interests us, as Christians, I would like to talk about a special type of fidelity that flourishes in our world and extends, in general, quite broadly, geographically, throughout the planet, and over time, throughout the history of humanity.

I'm talking about loyalty to evil!

• The first type of such fidelity is the fidelity of the ideology that hates humans and those that hate God (fascist, class, racist, sexist in both directions, religious, atheist, etc.).

  The goal of these ideologies is to defame, slander, and deceive supporters of opposing views in every possible way, trying to refute them.

Well, and as an example of loyalty to vicious ideologies, we recall the dialogue in chapter 44 of the prophet Jeremiah, his discussion with the Jews who fled to Egypt. (God speaks to the Jews through Jeremiah):

Jeremiah 44.4–7

‘Yet I sent all My servants the prophets over and over again, saying," Now do not do this abominable thing that I abhor. "
‘But they did not listen or pay attention to turn away from their evil, to stop burning sacrifices to other goddesses.
‘Therefore My anger and My anger poured out and burned in the cities of Judah and in the streets of Jerusalem, which were turned into ruins and desolation, as they are today.
'Now therefore, thus says the Lord God of hosts, the God of Israel:' Why do you do yourselves such great harm by cutting off from among yourselves a man and a woman, a child and a nursing child from the midst of Judah, with no remnant left?

Jeremiah 44: 15-17

Then all the men who knew that their wives were burning incense to other gods, along with all the women who were present, a great assembly, and all the people living in Lower and Upper Egypt, said to Jeremiah,
"We are not going to listen to the message that you have spoken to us in the name of the Lord!
We will certainly do everything we said we would do: We will burn incense to the queen of heaven and pour out drink offerings for her just as we and our ancestors, our kings and our officials did in the cities of Judah and in the streets of Jerusalem. At that time we had a lot of food and they were fine and did not suffer any harm.

This is how they formed a "loyalty" to paganism!

• The second type of fidelity to evil is fidelity to states, communities, organizations, parties whose purpose is to do evil, not their communities and individuals.
  On the basis of such fidelity, wars between countries take place, when there is a cry on one side of the border.

• And finally, the third type of fidelity to evil is the fidelity and even the worship of individual people, what any normal person will say: this is a villain or a moral monster!

However, those people always had and still have many fans.

Unfortunately, fidelity in worshiping the living and dead idols is very popular in human society.

Well, what can we say about the faithful listed by us? True to evil! True to ideologies, organizations and people...

In my opinion, these are impenetrable fools who are unable to distinguish the good from the bad and the moral from the immoral. Or people with mental pathologies who only need medical attention.

And now let's leave this social turn alone and move on to fidelity as a positive phenomenon in the human community.

God's faithfulness, as a rule.

And to start, remember that the faithful is one of God's names.
This is what Moses calls it in Deuteronomy:

Deuteronomy 7: 9

Know, then, that Jehovah your God is God, faithful God, who keeps the covenant and mercy to those who love him and keep his commandments, up to a thousand generations.

Thus says Saul in 1 Samuel:

1 Samuel 15:29

Furthermore, he who is the Glory of Israel will not lie, nor will he repent, because he is not a man to repent.
And he said: I have sinned; But I beg you to honor me before the elders of my people and before Israel, and return with me to worship the Lord your God.
And Samuel returned after Saul, and Saul worshiped Jehovah.

This is what the apostle John calls it in the book of Revelation:

Revelation 19: 11-13

And I saw heaven open, and behold a white horse; and he who sat upon him was called Faithful and True, and in righteousness he judges and makes war.
His eyes were like a flame of fire, and on his head were many crowns; and he had a written name that nobody knew but himself.
And he was dressed in a blood-soaked garment: and his name is called The Word of God.

And the Lord confirmed his faithfulness many times in practice. He concluded several agreements with humanity and, for his part, executed them sacredly.

1- He made the first covenant with Adam and Eve. And it still does.
2- He made the second covenant with Noah. And it also does it unconditionally.
3- He made the third covenant with Abraham and fulfilled it.
4- He made the fourth covenant through Moses with Israel and fulfilled it.
5- He made the fifth covenant through Jesus Christ with the Christians.

And Scripture has repeatedly said about the fact that God keeps his faithfulness:

Exodus 34: 6

Then the LORD passed before him and proclaimed: The LORD, the LORD, a compassionate and gracious God, slow to anger and abundant in mercy and faithfulness.

Lamentations 3: 22-23

That by Jehovah's mercy we have not been consumed, because his mercies never waned; new are every morning. Great is your fidelity!

And waiting for the Lord's faithfulness is our obligation, it will not embarrass you! Even if a person is unfaithful, God remains faithful:

2 Timothy 2:13

if we are unfaithful, He remains faithful, because he cannot deny himself.

Numbers 23: 18-20

Balaam then uttered this prophecy:
"Balak, son of Sipor, listen carefully.
God is not like mortals: he does not lie or change his mind. When he says a thing, he does it. When you make a promise, you keep it.

I would like to end this argument from faithfulness calling Jesus to the believers of the church of the city of Smyrna in the Book of Revelations of John:

"Do not be afraid of anything you need to endure ... Be faithful until death, and I will give you the crown of life!" Revelations.2: 10

Reference for information:

https://gracelovelife.com/15-bible-verses-on-gods-faithfulness/
https://reflexionesdelpastor.com/que-dice-la-biblia-acerca-de-la-fidelidad/
https://www.bibletools.org/index.cfm/fuseaction/Topical.show/RTD/cgg/ID/19549/Gods-Fidelity.htm