14 And God said, “Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons,[f] and for days and years, 15 and let them be lights in the expanse of the heavens to give light upon the earth.” And it was so. 16 And God made the two great lights—the greater light to rule the day and the lesser light to rule the night—and the stars. 17 And God set them in the expanse of the heavens to give light on the earth, 18 to rule over the day and over the night, and to separate the light from the darkness. And God saw that it was good. 19 And there was evening and there was morning, the fourth day. Genesis 1 (NKJV)

The Young Universe/Earth model advocates consider those who don’t interpret Genesis 1:14,15 to be an ex nihilo creation to have a deficient concern for the biblical text. This would also imply that the YBC belief in an undated universe indicates a less fundamental view of biblical doctrine. But Bible Truth Publishers is the vehicle of conservative Brethren writers from decades past. Note this quotation from William Kelly that Day Four describes the purposing of the solar heavens instead of their initial creation out of nothing:

Then we are told [Gen. 1: that “God made,” not created, “the two great lights.” The language is never varied without purpose. Rosenmüller the younger was an admirable Hebraist, and certainly free enough in his handling of scripture; yet he has no hesitation in his discussion of this question formally, but insists that the genuine force of the construction is not “fiant luminaria” (i.e., let lights be made), but “inserviant in expanso coelorum”, i.e., serve in the expanse of the heavens). He compares he singular with the plural of the Hebrew verb for being, and deduces the inference that the language can only express the determination of the luminaries to some fixed uses for the world, and not to their production. (Kelly, William. In The Beginning – and the Adamic Earth, 1891, reprint. 1970, Bible Truth Publishers, pp. 62-63.)