how to tell him?

[ChadCoxRox]

oh no, it's not a bad thing certainly, it's just that one of the things bothering about is that i feel i can reason with him about the "sexuality" but also admitting to him that i'm an atheist...i just don't how he will handle it since we all know where atheists go( will he be upset, become depressed, etc.) and i just don't like making people feel terrible.

Well if you don't believe in heaven or hell, then surely you believe in getting as much "heaven" in the here-and-now as reasonably possible. If your dad can appreciate that despite his fear/worry about afterlife then that may be an acceptable compromise. You might just keep it from him all together unless he presses you. And get your relief by talking to someone else to get it all off your chest on a regular basis until you have it in an acceptable perspective to let the worry go.

Best wishes!