'Light' in the Bible

As for those who at one time saw the light, tasting the good things from heaven, and having their part in the Holy Spirit,

But give thought to the days after you had seen the light, when you went through a great war of troubles;

And have you completely forgotten the exhortation which instructs you as sons? "My son, do not make light of the Lord's discipline, or give up [when you] are corrected by him.