John did write in 1 John 1:9 "He is faithful and just to forgive you", but that was a letter written to people who were already Christians.  There is a gate, a door we must enter through in order to become Christians. 

If forgiveness was freely given to anyone who asked, regardless of what basis they were asking for it, then all religious people of any faith would be "saved" when they ask forgiveness.  Whether Muslim, Hindu or Buddhist, all could be forgiven in this manner.  But Jesus said narrow is the gate, and few are they that find it. 

If universal forgiveness to all religions were possible then why did Jesus bother to die on the cross? 

 Click here to read about the gate I am talking about.