Hashkafa 101

"כי אני יהוה לא שניתי ואתם בני יעקב לא כליתם"
For I, the LORD, do not change; therefore you, O sons of Jacob, are not consumed
Malachi 3-6

ואינו משתנה שאין לו דבר שיגרום לו שינוי ואין לו לא מות ולא חיים כחיי הגוף החי ולא סכלות ולא חכמה כחכמת האיש החכם לא שינה ולא הקיצה ולא כעס ולא שחוק ולא שמחה ולא עצבות ולא שתיקה ולא דבור כדבור בני אדם
and He does not change, for there is nothing that can cause change in Him. There does not exist in Him... anger or laughter, happiness or sadness...”
Yad 1:11

Shifra asks:
If someone is sick, or there is a drought for example we are encourage to daven to hashem to beg him to change his decree. It is not because we think god is deficient that is just the way Chazal has instructed us to act... It is a very commonly accepted belief among orthodox jews that heavenly decrees can be altered by prayer - what do you think you are doing in shul on Yom Kippur all day?!

DovBear answers:
We're changing OURSELVES so that the unchangable God will relate to us differently. Fire makes one thing black, another white, one thing hard, another soft. The change occurs not because the fire is different but because the objects that come in contact with it are different (Rambam)