Hello hippikon,
Long time no see!
Just so you know, ... that picture of "Jesus" is exactly how the 'world's Jesus' (including the WTBTS) looks like. And it was those "good-looking" Jesus' that my Lord warned me against. I could always hear him say, 'That's not me. I look NOTHING like that.' In a vision, I once saw someone who looked soo much like "Jesus" that all these 'sheep were running to him. I thought it was my Lord but I 'heard' the spirit say "Don't be fooled by his outward appearance, for he is NOT me." Then later on when I looked a little more carefully toward that "Jesus" he was slaughtering the sheep just as your picture was doing it. But, the sheep LOVED it!
Anyways...
you asked, "Why is God invisible?"
The reason?
The Father is invisible because the flesh.. (which is SO consumed with outward beauty) could NOT handle God's appearance. For God is not beautiful in 'outward appearance' but beautiful in inward appearance.
Why is the Son invisible?
Because the "world" beholds him no more.... BUT those who belong to him by his spirit, can literally see him. Some of us have actually 'seen his figure,' his actual appearance. He said the world would no longer behold him, but those who belong to him are welcome to see his figure. For he loves them and 'plainly shows himself to them.' Anyone asking can recieve it. Those who don't believe it, don't see him. Those who do believe it, will see him.
Peace!
Aaron