What are the differences between Martin Luther and John Calvin?

Both Luther and Calvin came to their positions from
intense personal inner struggle. Both had originally been clerics of the Catholic
Church; Luther had been a German professor, Calvin a French lawyer and humanist.
Luther's writings were in response to the corruption that was prevalent in the Catholic
Church, primarily the sale of indulgences; Calvin responded to his own inner conviction
of the utter depravity of man.

Luther said that salvation
comes from faith alone; the Pope had no special authority; rather he spoke of the
"priesthood of all believers." Luther argued that there were only three sacraments as
opposed to the seven practiced by the church; those in which Jesus actually participated
while on earth.

Calvin frequently spoke of the “abyss” over
which mankind hovered. The most important element of his theology was the doctrine of
predestination. Calvin wrote that God was sublime, and so
overwhelming and awe-inspiring that human beings were insignificant, sinful, and
unworthy. Yet God was also a God of love, who planned from the beginning of the universe
to the end of time, and selected some human beings, the “elect,” for salvation; others
were selected for damnation. The following quote is from
Calvin:

readability="11">

Predestination we call the eternal decree of God
by which He determined in Himself what would have to become of every individual of
mankind. For they are not all created with a similar destiny; but eternal life is
foreordained for some and eternal damnation for others. Every person, therefore, being
created for one or the other of these two ends, we say is predestined to life or to
death.

Predestination was the
area in which Luther and Calvin disagreed most. Where Luther had emphasized
reconciliation to God through faith, Calvin emphasized obedience to His will. Calvin’s
position on the Eucharist also differed with Luther. He argued that there was a
“spiritual” presence. There was such a close connection between the communion host and
the gift of salvation which it symbolizes that one
can

“easily
pass from one to the other. For why should the Lord put in your hand the symbol of his
body unless it was to assure you that you really participate in
it?”

Luther's teaching was of
consubstantiation: Christ was present at the Eucharist, but the
bread and wine were not transformed, as had been taught by the Catholic
Church.