Aqaaid

Deleting a recording of an incorrect statement one made

Q: If someone did a radio play for university coursework and their character in the script said an utterance of shirk, for example if they said "christ" and they recorded this, does that mean the sin is there and even if I deleted the recordings but there might be a file somewhere.

I knew it was wrong but I thought because its a character and I'm speaking the lines of that so it doesn't matter too much. Then I remembered how bad it was and the fact that it was part of the radio play. Now I'm trying to delete the recordings and finding out if it's anywhere else on my laptop. I deleted them and edited it out of the radio play but I am still stressed. Its because its recorded and I feel like if the cache or bit of the recording is still in the computer somewhere then is it still shirk?

Superstitious beliefs

Q: Please expand on the subject of superstitious beliefs in Islam. E.g. whistling in the house or cutting paper and rocking. Apart from the many other common household beliefs that are becoming a daily problem. 

Thoughts of kufr

Q: I live in Iran and I have problem with my life. Sometimes when I am playing games or prayer I always say bad words at Allah in my heart. I don't know what's wrong with me and I don't want to say things like that but it always happens... I'm scared because I am feeling like I'm a kafir by saying bad words at Allah. What should I do now? Am I a kafir?