The correct spelling for the phrase "study at atheist" would be "study of atheism." The pronunciation of this phrase would be [ˈstʌdi əv ˈeɪθiˌɪzəm] in IPA phonetic transcription. This means that the stress is on the first syllable of "study" and on the second syllable of "atheism." The "th" sound in "atheism" is pronounced as a voiceless interdental fricative [θ], whereas the "th" in "study" is pronounced as a voiced dental fricative [ð]. By using the correct spelling and pronunciation, we can effectively communicate our ideas about atheism in an accurate and clear manner.