God is almighty, but it does not mean that he has unlimited power - it only means that he has all types of power, everywhere - but his power is not unlimited.
The devil - or Satan Lucifer - also has a lot of power.
Have you read The Apocryph, that was outlawed at a catholic church meeting in Rome year 400 A. D. (after christ) ... ?
This is what The Apocryph says:
God created the universe in six days, and rested at day seven.
And at day eight he created Satan Lucifer - the archangel of light - and asked him to run the world for a while when he was resting.
He gave Satan Lucifer power equal to his own power, the same amount of power as his own power, and a free will.
But Satan Lucifer decided to be evil, start a war and take over Jehovas place.
First war in heaven was won by Satan Lucifer, Jehova was sent to prison for sixty days - and in sixty days Satan Lucifer created ten times more evil things than all the good things Jehova created in six days.
Second war in heaven was started by angel Peter, 144 000 angels against 200 000 of Satan Lucifers demons.
Peter won the war, Satan Lucifer was sent to prison, Jehova was liberated - and it will be a struggle until the end of the time against all evil things Satan Lucifer created in sixty days.
But a day can be thousands of years - and thousands of years can be a day ...
