Can anyone explain what is wrong with giving or receiving something with the left hand? I find this annoying when people say I shouldn't give or receive with it. Are both hands not created by God?

What do you think?

Oh the dreaded left hand!

I believe some West Africans also follow this pattern. I’m not sure as to how this came about or what purpose it serves other than customary behaviour – but like you I’m curious to know.
But I also think this convention may be seen to portray alignment and some sort of structure eliminating waywardness just like driving on either the right or left side of the road. Although personally I still believe there is a story behind this because some senior Africans deem it as almost sacrilege to use the left hand.

However the only gripe I have is when a potential left handed child is forced to use their right hand (like my brother when he was a toddler). I believe that type of tampering alters the sequence of the child.

But I've been so conditioned in this peculiar custom that even when I'm with outsiders I'm always conscious to use my right hand.

I've read that traditionally in regions where water is not plentiful, it is usual to eat with your left hand, just because the right hand is the giving and receiving things all the time, so it would be less neat.
It may be an explanation.
In South America (Uruguay, Argentina, Brazil, Paraguay) is an infusion drink called "mate" in all cases that "mate" should be delivered and / or received by the right hand. Otherwise be considered a sign of contempt.