What is fundamentalist christianity?

My understanding of fundamental Christianity is the elementary teachings aboutChrist and have not moved forward to maturity. 

Hence fundamentalists are a group of people who are stuck in old ways of thinking, don't want to put away childish things and those who have refused to progress, grow and mature. 

It is based on Hebrews 6: Therefore let us go on and get past the elementary stage in the teachings and doctrine of Christ (the Messiah), advancing steadily toward the completeness and perfection that belong to spiritual maturity. Let us not again be laying the foundation of repentance and abandonment of dead works (dead formalism) and of the faith [by which you turned] to God,"

Fundamentalist Christianity holds on to the outdated traditions of Judaism and borrowed traditions of paganism that revolve around rituals and sacrifices. In a recent video on YouTube, Carlton Pearson pointed out that Christianity itself is a combination of ancient traditions, including astrology, and so it is not so much about a historical Jesus but about the principle of Christ in every person.

Spiritual progress, maturity or evolution then, is about moving beyond the illusion of separation and beyond religious rites and institutions, and embracing the mystery of Christ in every person, and reconnecting each person to Love and our true divine self in consciousness.