Answer:
I may only be given but never bought. Sinners seek me but saints do not. (one word).
I'm blue at day and black at night. I do contain some creatures born and died. What am I?
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. Sooner or later everybody needs my help yet many people are afraid to let me help them.
If you lose me you may cause people around you to lose me too.
Weight in my belly, trees on my back, nails in my ribs, feet I do lack. What am I?
I touch the Earth, I touch the sky, but if I touch you, you’ll likely die. What am I?