I used to go to a Charismatic church also. And the things you describe sound very familiar. I heard about oil, and even feathers appearing that some people were claiming to be from angels. I also saw slaying of the spirit and praying in tongues, etc.
It is good you don't readily accept all this as coming from God, because it is not from God, even if some of these things are miraculous. Perhaps the Holy Spirit is warning you in your spirit to be careful and that is why you have questions about all of this.
We know from the Bible that not all miracles come from God.
Jesus said: "For false Christs and false prophets will arise and will show great signs and wonders, so as to mislead, if possible, even the elect." (Matthew 24:24)
Jesus also said: "An evil and adulterous generation craves for a sign..." (Matthew 12:39).
Unfortunately, Charismatic (and Pentecostal) churches crave for signs. Instead of being strong in knowing and practicing the Bible, these churches are focused on signs and wonders. It is because of this unhealthy skew toward signs and wonders that opens up these churches for attacks from the enemy.
The Bible tells us that in the end times, even the Antichrist and false prophet will perform signs (Revelation 13:13). It also tells us that the evil one disguises himself as an angel of light (2 Corinthians 11:13-15). So it is no wonder that these enemy workers are inside the church trying to distract people from God and doing His will with material enticements and wonders.
For background on how Charismatic churches started, please see this:
https://www.gotquestions.org/Charismatic-movement.html
Let's go deeper into some of the phenomenon that are happening in Charismatic churches.
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SPEAKING IN TONGUES
First, if we believe in Jesus for our salvation, we have the Holy Spirit living in us regardless of whether we speak in tongues or not.
The Bible clearly tells us that we receive the Holy Spirit when we believe, not depending on any evidence of tongues:
“And you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in Him with a seal, the promised Holy Spirit, who is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession” (Ephesians 1:13-14).
And the Bible says not every Christian who has the Holy Spirit would speak in tongues:
"Now you are the body of Christ, and each one of you is a part of it. And God has placed in the church first of all apostles, second prophets, third teachers, then miracles, then gifts of healing, of helping, of guidance, and of different kinds of tongues. Are all apostles? Are all prophets? Are all teachers? Do all work miracles? Do all have gifts of healing? Do all speak in tongues? Do all interpret? Now eagerly desire the greater gifts." (1 Corinthians 12:27-31)
So where does the teaching of needing to speak in tongues come from?
Many people point to Acts 2 as evidence for needing to speak in tongues. However, this was the gift of languages.
There are two kinds of tongues: the tongue of the Spirit and of angels, and the languages of men. The Bible explains in 1 Corinthians 14 that speaking in the tongue of the Spirit does not help build up the body of Christ, because if no one interprets, no one understands. The tongues that were given to the disciples in Jerusalem in Acts 2 was the gift of languages. The disciples preached the gospel in different languages in order that people from many nations would believe (Acts 2:5-11). Today we have many native speakers who are Christians in their own nations. So we do not need the gift of languages as much as we did 2000 years ago.
The Bible says regarding the tongue of the Spirit, "For one who speaks in a tongue does not speak to men but to God; for no one understands, but in his spirit he speaks mysteries." (1 Corinthians 14:2).
"...however, in the church I desire to speak five words with my mind so that I may instruct others also, rather than ten thousand words in a tongue." (1 Corinthians 14:19)
So the main intent of spiritual gifts is to help other people and edify the church. Speaking in a tongue is not encouraged in church, because it does not edify the church, unless there is an interpreter. "If anyone speaks in a tongue, it should be by two or at the most three, and each in turn, and one must interpret; but if there is no interpreter, he must keep silent in the church; and let him speak to himself and to God." (1 Corinthians 14:27-28).
Therefore speaking in tongues in the church en masse is discouraged in the Bible. However, this is being practiced in Charismatic churches. If an unbeliever walks in, he would think all the people are mad and turn away.
Furthermore in some Charismatic churches, people speak in one or two syllables of non-sensical words repeatedly. They call this a tongue, but every language has many syllables. This false movement of tongues is non-sensical babbling and dishonors God.
Even darker, some people are able to speak in tongues of demons. While there is a tongue that good angels speak, there is also a tongue that evil angels speak. So beware that not all tongues are good. I have heard a person do this and it is incredibly disturbing.
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SLAYING IN THE SPIRIT
Slaying in the spirit is unbiblical. As believers, we belong to Christ and have the Holy Spirit within us. We do not need to be pushed down onto the floor or have some spiritual force over us that would spiritually push us over. Such acts have their roots in hypnosis. It is a hypnotic act that causes a person to cluck like a chicken, bark like a dog, or roll around on the floor. The person loses control over his own body and gives control to another.
In magic and hypnosis such things occur. This is not from God but from sorcery, which is forbidden in the Bible (Deuteronomy 18:10-11).
As children of the Most High, we are to conduct ourselves in dignity and possess our own vessels in sanctification and honor (1 Thessalonians 4:4).
The Holy Spirit is gentle and kind. He would never force a person to the floor or make a person roll around and bark. But people who don’t know God, pretend to be teachers, and mislead Christians.
“Likewise urge the young men to be sensible; in all things show yourself to be an example of good deeds, with purity in doctrine, dignified, sound in speech which is beyond reproach, so that the opponent will be put to shame, having nothing bad to say about us.” (Titus 2:6-8)
We are to live out God's words and be models for good deeds. Any act that is not dignified dishonors God and dishonors the person who falls victim to these evil influences.
The leaders who teach these false doctrines are knowingly or unknowingly blaspheming the Holy Spirit, because they teach what is false about the Holy Spirit and dishonors Him.
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OIL, GOLD, FEATHERS AND DIAMONDS
The enemy often uses objects to entice us. Things like anointing oil, gold dust, feathers and diamonds lead people away from focusing on God's word to focus on magical objects and the desire for wealth.
We need to understand that fallen angels were once good angels who learned from God. Some of God's creative powers and ability to work miracles were learned by these angels before their fall. After their fall, this knowledge did not disappear. But our enemies use this against us now.
They can use their ability to perform miracles and cause oil to flow from hands, and gold dust and diamonds to be sprinkled around, so that Christians are distracted by these unimportant things and do not focus on God's word.
During the time of Moses, sorcerers and magicians were able to perform some of the miracles Moses and Aaron performed. They were able to turn sticks into snakes (Exodus 7:12) and replicate the plague of frogs (Exodus 8:7).
But God did not teach the angels everything. As God performed more miracles through Moses, the magicians themselves acknowledged God's surpassing power (Exodus 8:19).
These objects of oil, gold, feathers, and diamonds are used to try to convince people to follow them (the objects) instead of God. The oil makes people think they are spiritual. The feathers symbolize protection. And gold and diamonds point to wealth. These are the enticing items of a prosperity gospel.
Would God do this? No.
Jesus said: "The foxes have holes and the birds of the air have nests, but the Son of Man has nowhere to lay His head." (Matthew 8:20). This means Jesus often didn't have a place to sleep at night while He was on earth.
And Jesus taught His disciples:
"No one can serve two masters; for either he will hate the one and love the other, or he will be devoted to one and despise the other. You cannot serve God and wealth." (Matthew 6:24)
All of Jesus' disciples lived frugally.
The apostle Paul said: "I have coveted no one’s silver or gold or clothes. You yourselves know that these hands ministered to my own needs and to the men who were with me. In everything I showed you that by working hard in this manner you must help the weak and remember the words of the Lord Jesus, that He Himself said, ‘It is more blessed to give than to receive.’ ” (Acts 20:33-35)
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Below are some other practices that are incredibly problematic in Charismatic churches.
DECREE AND DECLARE
https://www.gotquestions.org/decree-and-declare.html
DRUNK IN THE SPIRIT
https://www.gotquestions.org/drunk-in-the-Spirit.html
In light of all this, please consider going to a church that has the right focus.
The true test of a good church is whether that church treats the Bible as holy and practices what the Bible says. If a church disregards parts of God's word or teaches falsehood, it is not a good church to go to.
The Bible tells us to not grieve the Holy Spirit (Ephesians 4:30). Such churches are truly grieving the Spirit of God by teaching things that are not right and misleading many people.
Because false doctrine can be very subtle, it is best to not play with fire.
Proverbs advises:
"Can a man take fire in his bosom
And his clothes not be burned?
Or can a man walk on hot coals
And his feet not be scorched?" (Proverbs 6:27-28)
Ask God to help you find a good church. It is best to avoid places that could deceive us and lead us astray.