I am Jewish. We spell it without the o for a number of reasons. Mostly is is out of respect. The thought being you would not want the name of G-d written on something that could be thrown in the trash (or some similar thought). Of course that does not really apply to written words on the internet, but I still do it here because it is a habit and how I was raised.
Some would say that it's because God doesn't need to prove himself to mortals so we need to do it for each other.
Psalm 78:18 - 31
18 And they tempted God in their heart by asking meat for their lust.
19 Yea, they spake against God; they said, Can God furnish a table in the
20 Behold, he smote the rock, that the waters gushed out,
and the streams overflowed; can he give bread also? can he provide flesh for his people?
21 Therefore the LORD heard this, and was wroth:
so a fire was kindled against Jacob, and anger also came up against Israel;
22 Because they believed not in God, and trusted not in his salvation:
23 Though he had commanded the clouds from above, and opened the doors of heaven,
24 And had rained down manna upon them to eat, and had given them of the corn of heaven.
25 Man did eat angels' food: he sent them meat to the full.
26 He caused an east wind to blow in the heaven: and by his power he brought in the south wind.
27 He rained flesh also upon them as dust, and feathered fowls like as the sand of the sea:
28 And he let it fall in the midst of their camp, round about their habitations.
29 So they did eat, and were well filled: for he gave them their own desire;
30 They were not estranged from their lust. But while their meat was yet in their mouths,
31 The wrath of God came upon them, and slew the fattest of them, and smote
down the chosen men of Israel.
They tested the power of God and he killed the fattest of them.
But, I personally don't believe in God, so I don't believe that it is omnipotent. I think that people just so desperately need to believe in something that they're willing to make it be able to do anything. And when you believe in something that hard, the human will can manifest things to actually happen.
Is God willing to prevent evil, but not able? Then He is not omnipotent. Is He able, but not willing? Then He is malevolent. Is He both able and willing? Then whence cometh evil? Is He neither able nor willing? Then why call Him God?
It's because of love rather than need. God doesn't need us to do His will, He allows it, just as a parent allows a child to help them accomplish something that could have been completed without those little hands. It's out of love that we allow our children to help, not need.