Final answer:
The works of Copernicus and Kepler were not initially popular because they challenged the traditional geocentric view of the universe, which was supported by religious authorities and long-standing philosophical beliefs.
Step-by-step explanation:
Nicholas Copernicus's and Johannes Kepler's written works initially were not popular because they presented groundbreaking ideas that contradicted long-standing philosophical and religious beliefs of their time. Copernicus formulated the heliocentric theory, which positioned the Sun at the center of the solar system, contrary to the geocentric model supported by both ancient Greek philosophy and the Catholic Church.
Kepler, who built upon Copernicus's work, used Brahe's observations to develop his laws of planetary motion, further challenging established ideas. Experiments and empirical observations were undervalued in proving scientific truth during this era, making their evidence-based approaches controversial. Moreover, in stringent adherence to religious dogma, the Church declared the Copernican doctrine as 'false and absurd' due to inconsistencies with Scripture, leading to its suppression and limited dissemination.