Most mainstream "Christian" ministries list certain doctrines that you must believe in order for them to acknowledge you as a "real Christian". And this list is basically identical between ministries. These doctrines are said to be very important for the faith. However, there are other doctrines that these same ministries hold to that, if true, completely undermine the credibility of the "important" doctrines that you "must believe" in order to be a "real Christian".
All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness, [2 Timothy 3:16; NKJV]
Some ministries point out that the above verse literally says "all Scripture is God-breathed", then assert that this means that every word that is in the Bible comes directly from the mouth of God, and that the Bible is therefore inerrant. By the way, if you really want to be literal, then the verse should say "all writings are God-breathed". For the word translated as "Scripture" is the Greek word "graphe", which literally means "writing" or "document". Have fun explaining that one away. But they are right about it saying that it's "God-breathed".
These ministries that hold to the inerrancy doctrine because of their interpretation of 2 Timothy 3:16 typically invoke the slippery slope for anyone who does not accept their doctrine. They may also say that if you don't believe it, then you're not a "real Christian". In fact, some don't even allow you to challenge the interpretation given. So, how do these ministries show that they don't believe the doctrine that the entire Bible is the direct word of God? There are a few ways in which they do this. One of those ways is by ignoring the front of the book completely (with the exception being Genesis for some of these ministries). Here's another way.
1 Now the Spirit expressly says that in latter times some will depart from the faith, giving heed to deceiving spirits and doctrines of demons, 2 speaking lies in hypocrisy, having their own conscience seared with a hot iron, 3 forbidding to marry, and commanding to abstain from foods which God created to be received with thanksgiving by those who believe and know the truth. [1 Timothy 4:1-3; NKJV]
What would happen, say, if someone pointed out that God himself commanded us not to eat the flesh of pigs (Leviticus 11:7-8)? Well, these ministries will all quote 1 Timothy 4:1-3 and assert that such people are teaching doctrines of demons. That's right, those who claim that the Bible is inerrant call a command of God "doctrines of demons" without any hesitation! Of course, if they call a command of God "doctrines of demons", then that also means that they are calling God himself a demon. This same God that they are calling a demon gave us Jesus, which also means they have completely undermined the Gospel! By the way, anyone who calls even one command of God "doctrines of demons" calls all of God's commands "doctrines of demons", for the same God gave all of the commandments found in Torah. Also, if their interpretation of 1 Timothy 4:1-3 is correct, then the Bible is not inerrant and they really should not be listening to Paul. By the way, it's God's Law that determines what is or is not food. And the definition of "food" that Paul is using in that passage is that which is found in God's Law. And God says that pigs are not food.
For the priesthood being changed, of necessity there is also a change of the law. [Hebrews 7:12; NKJV]
Here's a passage that many of these ministries will use to justify not keeping God's Law. The Greek words translated as "change" in this passage is "metatithemi" and "metathesis" respectively. These words literally mean "to transfer". Also, Psalm 119:160 says that all of God's judgements are eternal. The Law of God is a list of God's judgements concerning what is right and wrong. Some of these ministries, when confronted with the question of "who created God", will rightly point-out that God is eternal and does not change. If that which is eternal does not change, then that means God's Law also does not change, for it is said to be eternal. So if their interpretation of Hebrews 7:12 is correct, that means that Psalm 119 is wrong, which means that the Bible is not inerrant.
Here's another point: If the Law needs to be changed, then that proves the Law to be in error. But if the Law is in error, then the Bible is not inerrant. And if their interpretation of Hebrews 7:12 is correct, yet the Law is not changed, then it means that Hebrews 7:12 is in error, and the Bible is not inerrant. There are more ways that they undermine this doctrine, but it's time to move on to the next doctrine that they undermine.
That doctrine, or rather, doctrines, would be the Trinity and the Deity of Jesus. While some ministries make it their job to prove the inerrancy doctrine to those who don't believe it, no ministry in mainstream Christianity allows you to challenge the Trinity. And most don't allow you to challenge the Deity of Jesus, though all of them show that the latter is able to easily withstand scrutiny. Now, whether the Trinity is right or wrong is beyond the scope of this post. This post will simply cover how these ministries undermine the credibility of the Trinity (and the Deity of Jesus).
In one of the excuses that these ministries use to rebel against God's Law, they will assert that the Law is impossible to keep, or that it's somehow burdensome, and that Jesus freed us from God's Law. Are you noticing a pattern in how these "most important doctrines" are being undermined? One aspect of the Trinity is that Jesus is the same God that gave us the Law of God. But when it comes to God's Law, the God of the "Old Testament" is portrayed as an oppressive being while Jesus is portrayed as having freed us from said "oppressive" being. That means that Jesus is a different god than the one that gave us his law.
By the way, remember how I pointed-out that these ministries will call certain commands of God "doctrines of demons" without hesitation? Well, if Jesus is God, but what we call the Law of God is really "doctrines of demons", then that also means that Jesus is not the same God who gave us his law. Yet if you insist that he is and hold that some of his commands are "doctrines of demons", then you're believing in the wrong god, and the wrong trinity! Oh, by the way:
20 To the Jews I became like a Jew, to win the Jews. To those under the law I became like one under the law (though I myself am not under the law), so as to win those under the law. 21 To those not having the law I became like one not having the law (though I am not free from God’s law but am under Christ’s law), so as to win those not having the law. [1 Corinthians 9:20-21; NIV]
This passage is often quoted like this:
In 1 Corinthians 9:20, it says that we are not under [or "we are free from"] God's Law. In verse 21, it says that we are under Christ's Law.
See what happened? They misquoted 1 Corinthians 9:20-21 to make God's Law be in direct opposition to Christ's Law. "We are not under God's Law, we are under Christ's Law." But if this is true, then that means that Jesus is not the same God that gave us his law. Also note that in all of these examples, the doctrine of the Deity of Jesus is also thrown away for the sake of rebelling against God's Law. Oh, and remember back to the post exposing the serpent's deception in Genesis 3? The very first deception was making God's Law look oppressive! In fact, the occult teaches that a serpent freed us from an oppressive god through knowledge. If you replace "serpent" with "Jesus", and replace "knowledge" with "the cross", you have Church doctrine!
All this goes to show you which doctrines are actually important to these ministries. They'll be quick to say "if you don't believe the Trinity, you're not a real Christian", yet they will just throw that doctrine to the side if it means they don't have to obey God's commandments. Some will also say "the Bible is the inerrant Word of God", and "rejecting Biblical inerrancy is dangerous to your faith", but have no problem portraying the front of the book as being in error for the sake of their idolatry (rebellion against God's commands), so long as nobody catches onto the fact that they're doing just that. Remember, you can either do things God's way, or make for yourself golden calves. If you refuse the former, you are doing the latter by definition.
And if you think that things couldn't get any worse. Well, it's about to get even worse. Revelation 13:11-18 describes a one world religion and a mark that everyone must take if they want to live. This mark is known as "the mark of the beast". Now, nobody seems to know what exactly this mark is. But there are a lot of claims about what this mark is, and even claims about it's precursors. Which of these claims is correct is beyond the scope of this post. But some ministries will dismiss the mark of the beast as mere "conspiracy theory". This tells you all you need to know about such ministries. Such ministries are part of the system that will bring about the mark of the beast. And they want to make sure that you cannot identify it as such, so that when it comes, you willingly take it, unaware of what it really is. In this case, they have sacrificed the inerrancy doctrine by calling Revelation false prophecies, because they are part of a (probably global) propaganda campaign designed to trick you into getting the mark of the beast!