The same as it would take for me to not believe that Jesus is God's Son...............not a chance in this world would ever convince me differently...............remember I was a globe earther before I investigated the matter, my whole premise of investigation was to disprove the flat earth theory....................the only thing that stood in the corner of the flat earth theory for me, was the word of God and how the entire bible is filled with flat earth language and was written by flat earth believers....................then when you start realizing that we do see much further than the curve allows and start putting all the pieces together you can see heliocentrism is a satanic deception of grande proportions............just looking up at the stars at night you can see the stars are laid out in a dome shape, the sun shining down through the clouds with crepuscular rays shows the sun is close and local