If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.  1 John 1:9

Pope Francis stated that he would offer "indulgences" to Twitter followers.  The dictionary describes indulgences as "a remission of the temporal punishment for sin after its guilt has been forgiven."  According to the Catholic church, an indulgence is NOT:

• Permission to commit sin
• A pardon to future sin
• Forgiveness of the guilt of sin
• An exemption from the law or restitution from consequences of sin
• Immunity from temptation
• A pardon that secures salvation

Taken from the New Catholic Encyclopedia (http://www.newadvent.org/cathen/07783a.htm)

So an indulgence is the full or partial remission of temporal punishment for sins after the sinner confesses.  Under Catholic teaching, every sin must be purified either here on earth or after death in a state called purgatory.  Sadly, the practice of offering indulgences became corrupt during the time of Martin Luther, where the church was making money off the practice.

From http://law2.umkc.edu/faculty/projects/ftrials/luther/lutherindulgences.html

So are indulgences necessary?

ONLY GOD CAN FORGIVE
The Pharisees and the teachers of the law began thinking to themselves, “Who is this fellow who speaks blasphemy? Who can forgive sins but God alone?”  Luke 5:21

In the time of Jesus, the religious leaders would never imagine that they had any power to forgive sins.  They were shocked Jesus offered forgiveness.  "A man?  Only God can do that!"

ONE INDULGENCE IS NOT ENOUGH
“There is no one righteous, not even one;
  there is no one who understands;
  there is no one who seeks God.  Romans 3:10-11

Indulgences are only a partial forgiveness for specific sins.  There's a bigger problem.  We are all sinners who are fully corrupted by thousands of sins.  How many tweets do we need to send?

ONLY THE BLOOD OF CHRIST
In him we have redemption through his blood, the forgiveness of sins, in accordance with the riches of God’s grace... Ephesians 1:7
Only Jesus' death on the cross, the spilling of his blood, pays the price and offers completely forgiveness of all our sins.

CONFESSION IS COMPLETE FORGIVENESS
1 John 1:9 says if we confess (on our own, not with any outside help) God will forgive and cleanse us of ALL unrighteousness.  Once we are cleansed, we are forgiven - fully and completely - of all past, present and future sin.  We do not need to turn to anyone to ask for forgiveness.  We have direct access to God on our own.