Psalm 18: A criticism

Psalm 18: How many ways can I name to show how I disagree with the image of God portrayed as a vengeful being who favors a certain group of people? Psalm 18 exalts God for victory in a war against the speaker's enemies. However, some of the images give me pause when considering how God could be merciful and benevolent in one description and be a force of death and destruction later. My discomfort begins in verse 9, which the footnotes explain is an anthropomorphic representation of God's power. God will cause destruction by making the Earth heave and shudder as a preliminary assault on the speaker's enemies. The verse only gets more troubling as it goes on. It says, "...smoke rose from His nostrils and fire from His mouth consumed, coals blazed up around Him." Is it just me or does this sound more like a description of Satan than God? God, symbol of creation, Father of mankind, should not be consumed in flames and burning anyone--even people labeled as "enemies". It seems to me that one of the advantages to the existence of Satan is that God gets to remain benevolent and not punish people himself. If I believed in God and I read this psalm, the image of God engulfed in flames and breathing fire would make me pee my pants in fear.
The last line I want to point out (though there are many others) starts at verse 38 which states, "I pursued my enemies, caught them, turned not back till I wiped them out..you girt me with might for combat. You laid low my foes beneath me...I demolished them." This imagery of man fighting in the name of God and defeating his adversaries with God's help strikes me as a description of holy war. Throughout history the most damage that religion has done to society has been in similar forms of holy war. This reminds me of the topic I posted last Friday; it's terrifying to think that Jews living in Israel could read this psalm and interpret it as God's will to demolish Palestinians. If God is supposed to be the giver of life, I don't understand how these psalms could advocate God or his followers taking lives, even of "enemies". Psalm 51 that we discussed in class praised God for his benevolent forgiveness. Apparently, however, the same forgiveness does not apply to "enemies". This dichotomy of God being sympathetic and good to some people, but vengeful to others frustrates me and makes me question the bias and motives of the writers of these psalms. They obviously had a very different image of God than the depiction I would have chosen.