This is because repentance from sin is not enough. The Bible calls for unqualified repentance. Here's what this means.

Peter called the people to repent. Acts 2:38. The call to repent is a call for a complete turn around in your life. It's a call to stop walking (ordering conduct and conversation) with the world and to turn around to walk (order conduct and conversation) with God.

This call is not just about stopping sinning. It's about changing your attitudes, your thinking, your speech and your actions. It's about starting to take the same road Jesus takes in company with Him, having turned from the road of this world. Ro.12:1-2, Col.2:6-8.

Hence while the KJV and NKJV Bible versions translate Peter's call as "repent" the Amplified Bible translates it -

"Change your views and purpose to accept the will of God in your inner selves instead of rejecting it."

And the Expanded Translation says,

"Have a change of mind, that change being accompanied by abhorrence of and sorrow for your deed."

If we only ask our converts to confess sin, turn from sin and be sorry for sin we've only gone half way. God calls for a complete turn around in mind, views and purpose accompanied by abhorrence for sin.

Looking to convey the fullness of the nature of repentance, the prayer for salvation I have given on my web page says, "I now receive my privilege of becoming your child, I renounce citizenship of the kingdom of darkness and receive citizenship of the kingdom of your Son."

On The Virtual Church (a sister site) the following question was posted:

I searched your site and did not find actual 'how to' information on how to repent. I have found that I have misunderstood a lot of things in the past and would like to repent for all I have done wrong! Thanks.

I responded:

There is much misunderstanding about the word repent and what it means to repent. Nevertheless, the concept is a very straight forward one in scripture. The word repent is translated from the Greek word metanoia and this means to perform a right about face.

In other words, a call to repent is a call to turn completely around so as to walk with God in company with Him and His ways.

Perhaps though what was really on your mind was not repent but rather seek forgiveness. If that was the case then you'll find the apostle John explained exactly how to do this in 1 John 1:7 - 2:1.