An unthankful heart is found in somebody who doesn’t appreciate the things that God has given them. Each one of us have been given more than we’ll ever know, so there are no excuses for God’s children to be unthankful! Unthankfulness is looking at the negative, despite the positive.
God’s Word even tells us how people can be given over to homosexuality and all sorts of uncleanliness because they were unthankful:
Romans 1:21,26-27, “Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened… For this cause God gave them up unto vile affections: for even their women did change the natural use into that which is against nature: And likewise also the men, leaving the natural use of the woman, burned in their lust one toward another; men with men working that which is unseemly, and receiving in themselves that recompense of their error which was meet.”
Persecution Live 