Why are Christianity and occultism irreconcilable?

The reason they are incompatible is because one is of God and the other is of Satan.

We are readily apt to acknowledge the power of God, but appear reluctant to attribute any power or for that matter any fore knowledge to Satan. Yet Satan has both.

Job 1:7 through 12 NKJV And the LORD said to Satan, "From where do you come?" So Satan answered the LORD and said, "From going to and fro on the earth, and from walking back and forth on it." 8 Then the LORD said to Satan, "Have you considered My servant Job, that there is none like him on the earth, a blameless and upright man, one who fears God and shuns evil?" 9 So Satan answered the LORD and said, "Does Job fear God for nothing? Job 1:10 Have You not made a hedge around him, around his household, and around all that he has on every side? You have blessed the work of his hands, and his possessions have increased in the land. 11 But now, stretch out Your hand and touch all that he has, and he will surely curse You to Your face!" 12 And the LORD said to Satan, "Behold, all that he has is in your power; only do not lay a hand on his person." So Satan went out from the presence of the LORD.

What we learn from this passage is that Satan has power, but his power is subject to God. If you are unfamiliar with the plight of Job it is a good study in obedience to God. Even though God allowed Satan to take everything from Job except his life and apparently his wife; (who incidentally encouraged him to reject God), in the end God gave him even more than he lost.

In the following verse we see that Jesus appears to indicate that Angels; and Satan is one of those; have some, but not all foreknowledge.

Matthew 24:36 NKJV "But of that day and hour no one knows, not even the angels of heaven, but My Father only.

Occultism is basically an off shoot of Satanism, and far too many cases Satan is able to use his foreknowledge in occultism to lure away people from God, and occultism often leads to Satanism. That is the reason Jesus told us:

Acts 26:17 and 18 NKJV I will deliver you from the Jewish people, as well as from the Gentiles, to whom I now send you, 18 to open their eyes, in order to turn them from darkness to light, and from the power of Satan to God, that they may receive forgiveness of sins and an inheritance among those who are sanctified by faith in Me.'

We all too often forget that Satan is the Prince of the Earth.

Matthew 24:8 through 12 NKJV All these are the beginning of sorrows. 9 "Then they will deliver you up to tribulation and kill you, and you will be hated by all nations for My name's sake. 10 And then many will be offended, will betray one another, and will hate one another. 11 Then many false prophets will rise up and deceive many. 12 And because lawlessness will abound, the love of many will grow cold.

WE must be aware of Satan's snares and avoid them, certainly not all things that happen are the wiles of Satan, but those things which attract our hearts and minds from obedience to God. That is why Jesus warned us that all these are the beginning of sorrows.

While the classification what is occult is probably debatable, here is one of the reasons that they are irreconcilable:

As you mention, it shows pride - but not because we are trying to obtain power that belongs to God. God is more than willing to give us what we need, if we ask. And this includes, at times, miracles.

Notice however how much humility and faith is necessary for this.

1. One needs to accept God's authority over one's life
2. One needs to trust God in many ways (that he wants us good, that he will hear and answer our prayers)
3. We need to accept what he gives us, when he gives it to us

Occultism often tries to get to the blessings, without the obedience, so to say. Instead of praying for guidance, and trusting that He will guide, people turn to astrology. No faith required, no higher authority than oneself required (at least apart from some mindless "fate"). Here lies the pride.

Note that this is not an argument against science - although there are people that profess "believing in science" while actually having their own kind of superstitions and false beliefs.

(And occultism and superstition also often serve as substitute religion.)

At last, here is what the bible says about seeking guidance from the dead/spirits/mediums/whatnot:

Isaiah 8:19

And when they shall say unto you, Seek unto them that have familiar spirits and unto the wizards, that chirp and that mutter: should not a people seek unto their God? on behalf of the living should they seek unto the dead?

Why are Christianity and occultism irreconcilable?

The difference is as stark as night and day.

2 Corinthians 6:14-16 Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness? And what concord hath Christ with Belial? or what part hath he that believeth with an infidel? And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people.

Occultism is only one venue Satan uses to deceive and direct the world. Throughout the ages Satan has had success peddling his "secret" or "hidden" knowledge. Other than promoting smugness and blinding people to truth, it is difficult to see what is gained by the people drawn to seek this "knowledge".

Occultism is often associated with witchcraft. The description of rebellion as being similar to witchcraft at first seems a bit of a reach. Then when you consider that both at the core are about doing whatever you can to get what you want, you begin to see the common denominator, selfish desire.

1 Samuel 15:23 For rebellion is as the sin of witchcraft, and stubbornness is as iniquity and idolatry. Because thou hast rejected the word of the LORD, he hath also rejected thee from being king.

Christianity is about Jesus who is truth. Occultism is about blind self-deception and being given over to ones lusts and desires.

John 3:19 And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil.