First and foremost as a fundamentalist believer you must come to the realization that you are in the world but you are not of this world.
14I have given them your word and the world has hated them, for they are not of the world any more than I am of the world. John 17:14 NIV
With fundamentalist believers it is always us against them (the world). We chose to live in obedience to God and walk in righteousness while the world (non-believers) chose to pursue the pleasures of this world and of the flesh. As a fundamentalist you are convinced that everyone is a potential tool of Satan for the sole purpose of dragging you away from the Lord and leading your soul into eternal perdition. You are led to believe that you have been particularly chosen by God for salvation and that the majority of the people in this world will lose their souls to hell and eternal torment.
14“For many are invited, but few are chosen.” Matthew 22:14 NIV
13“Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it. 14But small is the gate and narrow the road that leads to life, and only a few find it. Matthew 7:13-14 NIV
When you are properly indoctrinated you come to believe that you are one of the chosen out of the billions of people in all the world. Not only do you believe this wholeheartedly but you are grateful that God has chosen you. The prospect of eternal life in the presence of the creator of all things excites you.
It is because of these core beliefs that fundamentalists who have so called experienced the gifts of the Holy Spirit in their lives are nearly impossible to convince that what they have experienced is easily explained away naturally or that what they believe can be debunked with simple logic. Even when a small seed of doubt is planted the very fear of offending God by daring to question or doubt your beliefs serve to keep you in line.
In my own personal experience I had read the Bible four times from cover to cover and the more I read it the more disgusted I became with my beliefs and with the God that I served. I was terrified about my doubts and the Bible made sure that I understood the gravity of my situation by providing nice threats for leaving the faith.
26If we deliberately keep on sinning after we have received the knowledge of the truth, no sacrifice for sins is left, 27but only a fearful expectation of judgment and of raging fire that will consume the enemies of God. 31It is a dreadful thing to fall into the hands of the living God. Hebrews 10:26-27;31
As you can see fear is also a very powerful force in Christianity. It is actually a virtue throughout the scriptures to fear the Lord and love him with all your heart. You demonstrate that love by living accordingly and in complete and total subjection and obedience to the Lord. After I had freed myself from all the chains of superstition through reason it was the fear that was the hardest to break free from. That nagging doubt about being wrong.