Mountains as Monuments
Mountains are big. They inspire awe in man. Since man's time on Earth is not even a blip on the geological timescale, mountains seem eternal. The term "everlasting hills" are meant to mean that mountains are monuments of God's eternal presence. Mountains as such are meant to be praised as signs of God's wonders.
"With the finest gifts of the age-old mountains and the best from the timeless hills" Deuteronomy 33:15
Mountains Close to God
Mountains are the highest land features on Earth. Their physical location close to the sky in turn becomes closeness to Heaven and God. God frequently calls man to mountains for communication.
The Old Testament is filled with mountains being close to God. Just take these two examples. God's pact with Noah (God's promises never to kill humanity on a large scale again) was formed on Mount Ararat in Genesis 8. Moses received the Ten Commandments (the basis for much of The Law) on Mount Sinai. The meeting was so important Mount Sinai was the middle point because both God and Moses travelled there "When the LORD came down to the top of Mount Sinai, he summoned Moses to the top of the mountain, and Moses went up to him." Exodus 19:20.
The New Testament divine mission both begins and ends on mountains. The Transfiguration, where Jesus is instructed on His mission, occurs on a mountain in Mathew 17:1-9. New Jerusalem, the church triumphant, is "seen" by Saint John while he is on a high mountain top in Revelation 21. Man sees the starting and ending process of the redemption of the world from mountains.
As the interior of the Earth is away from God, mountains are clearly close to him. Their majesty in physical form has been carried over into the divine.
The next blog post in this series will examine the Heavens.