Is this a good idea for starting the game? Usually I am a defensive player. Because of this, a few years ago, I created an opening set of moves, where I moved every other pawn forward 1 space, starting with pawn A2. To be more specific, I moved pawns 2A, 2C, 2E, and 2G to 3A, 3C, 3E, and 3G, respectively. 

There are ways to get through to row 1 using a queen or bishop, but except for one way (going diagonally to 1H with a queen), any piece will be immediately destroyed at almost any point in rows 1-4. That one way, using a queen to get to 1H, does do a lot of damage, because eventually it threatens the king, and is hard to be stopped.

I am an amateur chess player, so I do not know a lot about all of the tactics. To experienced chess players, this may look like a stupid question. I apologize for that.

Is this weakness enough to make the strategy not worth it, or is it still a good idea?
It's definitely not a good idea. If it were one, there would be a real opening for it. One problem with moving all your white-squared pawns 1 space forward, is that you lose so many moves developing your pieces. However, this is the 'small' disadvantage. The big one is, that all of your white squares are very weak.

Look at this position:



[fen ""]
1. a3 e5 2. c3 d5 3. e3 e4 4. g3 Nc6



Black just needs to put his pieces on nice squares like for example Ne5 or Nc4, Bg4 with Nf6. Also a disadvantage is that you lose much space. Your knights have nearly no squares, where they can move. Bc1 is completely useless.

If you lose your white-squared bishop, the black pieces will destroy you, because you can't defend all the white squares.