I know for a fact that we are not the first Christians who have faced a multitude of different teachings about Jesus, and have struggled with whose teachings to follow. All we have to do is look at the Early Church and we can see the problems that arose -- problems not unlike those we face today.
In Scripture, we can see an explosion of faith after the experience at Pentecost in the Book of Acts. Important Christian doctrines were established, such as the Incarnation of the Son of God (fully Deity and fully man); His death, burial, and resurrection; man's fallen nature and his need of a Savior; and Salvation is by God's grace through our faith in Jesus, just to name a few of the foundational doctrines. We see the Gospel Message [of the Kingdom] taken to distant lands, as the Apostles carried out their commission from Jesus to heal the sick, cast out demons, raise the dead, and preach that Kingdom Message.
But we can see that things must have become distorted as the decades and centuries passed, because the Church today doesn't teach that full Gospel; it has been reduced to the "Gospel of Salvation" alone. A fleeting glance at history shows us some of the problems that began arising in the Church, especially after the deaths of the Apostles and the martyrdom of Paul.
It isn't hard to imagine the early Christians meeting together for worship, and someone stepping forward to give their oral testimony of how they had heard an Apostle or other eyewitness tell of hearing the Lord say this or that. Or how they had seen the Lord heal the sick and give sight to the blind. Persecution of the new Christian faith soon thinned out these credible eyewitnesses, so that it wasn't long before very few persons remained who could give firsthand testimony regarding the teaching and activities of the Lord.
Fortunately for us, the Synoptic Gospels were soon written, verifying those oral testimonies and preserving them for posterity. But before we ascertain that the First Century Church was all sunshine and roses, we can see in Paul's writings and the epistle of James that differences of opinion and various disturbances among groups of Believers were beginning to cause dissension. Once that first generation of actual eyewitnesses and the second and third generation of those who had known the eyewitnesses were gone, the Church became subject to teachers and theologians who applied their own personal subjectivity to the Bible, and Christians had to decide whose teachings were the most credible and true to the original teachings of Jesus.
Nothing has changed in all these centuries. Today we are presented with a wide range of teachings -- all purported to be in alignment with Scripture. And as in the past centuries, we are presented with various "movements" that may or may not be in strict agreement with the Bible. Let's face it, the modern Christian has to be serious in their discernment. And it is not uncommon to agree with parts of a particular ministry, while having difficulty with other parts of its theology because it doesn't exactly align with Scripture.
There is such a huge number of teachers, Bible scholars, authors, ministers, and internet personalities for us to choose from, that it can be difficult to know how reliable their teachings are. We are rightfully concerned about being deceived; and any teacher or movement whose foundation is anti-Biblical should be dismissed. But at the same time, I have found that I can oftentimes get a nugget of Truth [from Biblical teachings] that I can apply to my theology, and then discard other parts of the message until I can study them further to see if I agree. As my husband often reminds me, "We can eat the meat and spit out the bones".
I can understand the hesitancy to accept any part of a teaching that may have questionable doctrine. But we must remember that even in the early Church there arose various opinions about what constituted "faith" because people misunderstood the teachings of Paul. For Paul, the word faith meant complete reliance upon Jesus Christ for salvation, and we know that this is correct teaching. But some converts were using the word faith to mean nothing more than they were members of Christian groups, and so on. So James, the brother of Jesus, and a leader of the Jerusalem Church, wrote his epistle to point out that Paul was speaking of "saving faith". He wrote to clarify that faith required "doing", not just hearing. These differing opinions did not mean that groups within the early Church discounted each other. Rather, it called for further study and clarification.
Also, during this first Century there was a difference in how some of the Jewish Christians regarded the concept of "works". For some it was the observance of the strict Jewish ceremonial law; while to others, it referenced charitable acts, or the fruits of Christian living. As you can see, there were differences of opinion that resulted in different theologies, although these disparate groups all proclaimed obedience to Jesus's teachings and Christianity.
I can only answer for myself, and tell you how I apply discernment. I try to follow Jesus's example in Mark, Chapter 9, when the Disciples came to Him and said, “Teacher, we saw someone casting out demons in Your name, and we tried to stop him because he was not following us.” And what was Jesus's reply? “Do not stop him, for no one who does a mighty work in My name will be able soon afterward to speak evil of Me. For the one who is not against us is for us". Jesus understood that not everyone would be part of the intimate group of His followers. But if they did the works that He did, and credited Him [instead of themselves], then they were doing the work of the Father and advancing the Kingdom. In effect, they were part of God's team and not Satan's -- for them, and not against them.
And that's what I try to do. I truly believe that God's character and knowledge are so great that He cannot download it all into one man or woman --- we are simply unable to contain the vastness of Him. But He can impart a piece of revelation to each of us -- this man might understand repentance at a really high Kingdom level; while this woman might receive God's wisdom regarding seeing in the spirit; and this person has had God's heart revealed in the area of Deliverance in partnership with the Holy Spirit. See what I'm saying?
I don't think it is possible to receive all God wants us to know about Him from one person. Yes, He has revealed Himself in the Bible, and it is up to us to seek Him through His written Word. But I also believe that He has no problem with us sharing what we have come to know through a heart seeking Truth. And just as Jesus said of those who were doing mighty works in His Name, we can discern whether today's teachers/scholars/authors/ministers are producing fruit for the Kingdom, and if they are, then it's safe to say they are for us, and not against us. It is not necessary to discard the sum total of their teachings. Use your God-given discernment, along with confirming Scripture and prayer. Then keep what has worth, and toss the rest. If you are seeking genuine Truth, the Holy Spirit within you will guide you and counsel you; He will not lead you astray. Above all else, God isn't interested in limiting what we can know about Him, and I want all the Truth about Him I can get!
Proverbs 2:3-5 "Yes, if you call out for insight and raise your voice for understanding, if you seek it like silver and search for it as for hidden treasures, then you will understand the fear of the Lord and find the knowledge of God".