Answer:
Martin Luther was a German monk who protested against the widely held believes in the Catholic church teachings of purification in purgatory before eventual entry to heaven. He called sale of indulgence.
Step-by-step explanation:
His "95 Theses challenged the catholic church against the sale of indulgence and which he believed to be corrupt. He was against the fact that peope could buy indulgence or the general believe that would be reduced punishment after death.
Indulgence in Catholic church means the remission done before God of the temporal punishment due to sin whose guilt has already been forgiven.
He was the only successful individual who stood against and challenged the catholic church on legitimacy of indulgence. He was however excommunicated and eventually set up the protestant movement.
His concern for the future was based on the fact that it will encourage people to go about doing all sorts of immorality and evilagainst humanity with the firm believe that their wealth will buy them pity from God and that assures them of place in the kingdom of God after death. Such teaching will breed corruption within the church.