Typically when it comes to charging system issues, troubleshooting with a multi-meter is the place to start. The charging system light is set to come on when it senses the vehicle voltage drop below a certain point for X amount of time. Given that you have a new battery and alternator, I would pose that the issue is somewhere in the wiring, causing either low alternator output or incorrect voltage sensing. Let us know what you find out.
Also, welcome to the forum. For future reference, the new member check-in is typically just for introducing yourself. For an issue such as this, I would recommend the 2nd Gen or Electrical sub-forum. If you need help with the website, you can always ask in "the lounge" under the "member's area."