In Thailand, there was a very famous monk who was chosen to represent Thailand in 1954 at the 6th Buddhist council in Burma who did not believe in rebirth (and who many Thai puthujjana considered to be a heretic & sutta-cutter). His life ended by natural causes at 87 years old.
A certain Sangharaga (Supreme Patriarch) who taught 'heaven & hell' where cultural beliefs that represent 'ancient geography' lived for 100 years, as follows:
"As we are so familiar, in religious sphere, the concept of heaven and hell is a very prominent belief. In many cases, it becomes the goal of religious practice itself. On this very subject, His Holiness critically analyses that the very concept and belief of heaven and hell in Buddhism is a cultural influence of indigenous culture and belief. He states: (I quote) ‘the subject of cosmology appeared in Buddhism is clearly can be seen that it is not ‘Buddhist teaching’ at all but an ancient geography. The concept and belief about it was included in Buddhist Canon merely because of strong influence of popular belief of the time. Later Commentaries further explain about heaven and hell in a greater detail distant itself from the original teaching of the Buddha. If Buddhism teaches such belief on heaven and hell it would not be Buddhism at all but an ancient geography. Buddha wouldn’t be the Buddha who delivered the Noble Truth and ‘timeless’ message for mankind.’ (p. 1) (end of the quote) He then shows in his teaching that the concept of heaven and hell in Buddhism are in fact symbolic, representing the quality of mind and spirituality instead. One can be in heaven and hell in this very earth and life. No need to wait until one dies..."
These monks with secular views lived to & died from old age.
Why do secular Buddhists not commit suicide?