"For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life."
- John 3:16

This portion of scripture is one of the most well known.  It is simple to understand, and contains the gospel message in one verse.

I have a tract in the Estonian (Fellowship Tract League) language that expounds upon John 3:16 in four different parts;
1. God's love for the world
2. Jesus was given
3. Every person may be saved from hell (reference is also made to Romans 3:23 and Revelation 20:15)
4. Every person may have everlasting life

These are such great truths that we, all people, ought to be saved.  It doesn't seem reasonable to me that after hearing and/or knowing these truths that a person would not then trust their soul to the hands of a loving God and Saviour.