One thing to remember when addressing this question is a simple idea that light is destructive to darkness. Consider these passages:
1 Thessalonians 5:2
2 For you yourselves know perfectly that the day of the Lord so comes as a thief in the night.
In the expression “day of the Lord” emphasize the word “day”, and in the “thief in the night” emphasize “night”. Now, read it outloud with these emphases. See how it reads differently? It’s about day vs night. “Day of the Lord” is to be taken to mean “day originating / deriving from the Lord”, i.e. genitive of source. The Lord comes in the night – meaning, in the midst of darkness. His mode of arrival is “as a thief” – i.e., unexpected, with the additional semantics of “inflicting loss”. The primary characteristic of his coming is “day”, or “light/brightness” (as opposed to “night/darkness”).
God isn’t in the business of killing, especially children, he’s in the business of restoring and healing. Also, he is a gentleman, not a violator, so he most definitely won’t violate one’s free will. If one’s free will could be violated, there would be no original sin in the garden of Eden – it was a matter of free choice.
With that said, there were times in ancient Israel’s history when certain military operations were carried out, and as with every war there was violence.
From all the Biblical references – Old Covenant and especially New Testament, all I see as far as the issue of fasting is concerned is that people eliminated food as they intensely focused on God, often times while seeking guidance before making a strategic decision. In 1 Corinthians 7, marital sexual relations are yet another thing that some people chose to eliminate, along with food, for a period of time:
1 Corinthians 7:5
5 Do not deprive one another except with consent for a time, that you may give yourselves to fasting and prayer; and come together again so that Satan does not tempt you because of your lack of self-control.
In our day, you can add to that list any of the distractions of the modern age, and if you take out some time to intensely focus on God – usually focusing on a specific aspect of your spiritual life or when faced with a strategic decision to make – you simply postpone or eliminate those for a time.