It is a caution not only mentioned throughout gospel, but it was the original advisory now called the third commandment. The Son-of-God is reported to have backed this up by saying—
"Every sin and blasphemy shall be forgiven unto men; but the blasphemy against the Spirit [God] shall not be forgiven. And whosoever shall speak a word against the Son of man, it shall be forgiven him; but whosoever shall speak against the Holy of Spirit, it shall not be forgiven him, neither in this world, nor in that which is to come" (Matthew 12:31-32; Mark 3:28-29; Luke 12:10).The blasphemers of God in this life, are the trickster spirits with which most of us contend -- the ones we know as devils and demons -- who ally themselves with Lucifer.
We, as fallen angels become human, are on the earth because we thought we wanted an autonomous life without God. Many of us haven't blasphemed God, but still may.
Therefore, although on a playground to pretend we have no God, if any of us want to get back to God's heaven, all we need do is call on the Son-of-God.
However, those who have blasphemed God, have divided God's earth into 'them and us' camps, much as school bullies separate easy victims from easier ones.
- THE EVIL are those obsessed by desires of self-reliance ruled by human sciences, narcissism, mysticism and the rote of religions. They often smirk at those who scare them.
- THE GOOD are the ones who will not blaspheme God during bumpy lives here, and as such, are the ones who, when partnered with God, will return to heaven. Good people can't smirk.
The best observation is that the good are always worried they aren't favorable enough to God, while the evil just don't care. How should we live then?
Well, as God made the world for us to enjoy everything in moderation, then enjoy it. All we need do is accept the Son-of-God for who he is, and grasp the hang-strap of God through the bumpy rides.
And when our processing is completed, we who have remained loyal to God will go home.
Blessings to you for trying to be decent, and for accepting and being accepted by the Son-of-God no matter by what name you know him. To those of you without God — too bad for you.