Read Draper's "Conflict between Science and Religion" which is a historical account of how some scientific ideas had to contend with religious prejudices—a book which, by the way, disproves the charge that Caliph Omar destroyed the great Library at Alexandria.
God reveals Himself to everybody at every instant of his life. It depends entirely on the spirituality or spiritual capacity of each individual to what extent he knows God and God's ways. The "spiritual capacity" is partly inherited from one's ancestors and partly acquired by faith and devotion, as well as by right conduct and good works.
نيست برلوح دلم جز الف قا متيار * چكنم حرف دگرياد نداد استادم The Alif of the Loved One's form is engraven on my heart, No other letter did my Shaikh ever to me impart—Hafiz.
See Note 2.
I have neither time nor space to explain the full significance of the Qur'anic verses I have quoted here.