“The angel replied, ‘The Holy Spirit will come upon you, and the power of the Most High will overshadow you. So the baby to be born will be holy, and he will be called the Son of God'” (Luke 1:35, NLT).
The Holy Spirit is a bit of a mystery to us mortals and people have done a lot of speculation about this third member of the Trinity. How fitting that Jesus was conceived through the power of the Holy Spirit, a mystery within a mystery.
The Amplified Bible says the power of the most high overshadowed Mary like a shining cloud. It’s a bit reminiscent of when the Spirit of God hovered over the waters in Genesis 1. His creative power was on display at creation and again as new life was created within Mary—the God-man, arriving on earth as a newborn who would go on to live a perfect life, lay that life down for the love of humankind and redeem the whole of creation. The mystery continues as the same shining cloud dwells in us today.