"And then if anyone says to you, 'Behold, here is the Christ'; or, 'Behold, He is there'; do not believe him;
for false Christs and false prophets will arise,
and will show signs and wonders,
in order to lead astray, if possible, the elect.
But take heed; behold, I have told you everything in advance."
— Mark 13:21-23 NASB

Learning our doctrines and the basics of our faith can be a bit of a daunting challenge. It takes time and perseverance, plus a great deal of reading and listening to good, solid, Bible-based teachings.
One thing that made learning the basics of the faith more interesting for me was studying the cults as well as aberrant teachings. Again, I want to clarify that honest people disagree on certain nonessentials. We must walk in love as well as truth. Disagreements on nonessentials does not mean that someone is a heretic or a cultist. It has been rightly said that the Word of God is a sword, not a club; we do not beat people over the head with the truth. Stop looking at me like that...
Many people have been drawn away from the faith because they were not grounded in the Word of God. Cults recruit church people away from their church. Those nice, clean, pleasant people at the door want to offer something that many people are not getting from their churches. Often, it is because so many churches today are simply religious social clubs and have very little to offer. However, it is also because too many church people (I am reluctant to call them "Christians" or "Followers of Jesus" because their commitment is so nominal) do not know what the Bible teaches. (And not only cults that claim to be Christian, but other religions entirely.)
Helen Hulse, from the Mormon Missions Midwest Outreach, said:
Sadly some are converted into the LDS Church and are members today because they did not read nor study their Bibles for themselves. People as Rocky has stated over and over in our seminars around the country "Run to your Bible"; if you know... what is between the pages you'll be prepared when a knock comes at your door selling a false religion. If you meet your nice neighbors or co-workers and they invite you to their church, you'll know false teaching when you hear it. You must know what you stand for or you'll fall for anything that sounds and looks good...Cowboy Bob, thanks much. It's important to remember Rocky's advice of "Run to your Bible" it's what he does and has always advised others to do when we are speaking in churches. How is it possible to just sit in any church and be told what to believe? We all need to know what we believe and why we believe it, in order to share the hope that is within us.

I learned quite a bit about my own beliefs when studying cults. By far, one of the best possible references is Dr. Walter Martin's Kingdom of the Cults. Also, there are many resources available online, and I have given you a few links. If you were checking the links I gave, one of my favorites kept recurring: The Christian Apologetics and Research Ministry. There is a wealth of material there on cults and false teachings. At the top of this page, I have "Resources for Christians" that can keep you busy and informed for quite a long time.
Let me add that "Answers in Genesis" can not only give you a good basis on refuting evolutionism and compromise with evolution, but they have other good teachings as well.
It is my recommendation that you avoid letting the cultists into your home until you are well prepared in knowing what and why you believe. Then, you can witness to the cultist, the believer in false doctrines and others. But never buy their materials or give them money!