My friend is a Hindu believer but he says that God is not capable of being worshiped because He do does not look after the poor. All the sufferings in the world are because of God. Why does He not care about the world?
"God is not capable of being worshiped because he do does not look after the poor"
I would like you to encourage your friend to think that on what basis he says that being worshiped is conditional to looking after poor.
We worship God not because he looks or does not look after poor, but because He is the Creator. Being the Creator, He is also absolutely Perfect in every sense. So He deserves to be worshiped.
It is important to separate this (why worshiping Him) from matters like why He does not take care of the poor.
Only after appreciating the above point we can look at other aspects of your friend's argument:
1. God does not look after the poor
2. All the suffering in the world is because of God
3. God does not care about the world
All the above statements are based on an understanding of God and His design that to us, Muslims, is not correct. We do not believe that God has put us in this world to take care of us and make sure we will be happy. If this was the design of creation then most certainly we could say that god has failed in his work and therefore he is not the absolute perfect being, which then means he cannot be The Creator. This then means he does not deserve to be worshiped.
However as I stated above, the design of God is something different. We read in the Qur'an that the purpose of putting us in this world is to give us challenges (67:2). This, we can understand, is for us to excel and reveal our potentials. Those of us who overall succeeds in these challenges will be in heaven in the hereafter and those who do not succeed due to their own arrogance may go to hell in the hereafter unless God forgives them.
Looking from the above perspective, this world is not supposed to be our only chance of living where we would expect to live happily for ever. This world is only a temporary platform for us to be challenged, to become better and better, and to therefore get an everlasting happy life in the hereafter with the blessing of the Almighty.
Looking from this perspective, the sufferings that your friend mentioned are in fact one of the perfectly appropriate ingredients of the design of the Almighty in our life. The one who suffers, the one who sees the suffering and the one who has no idea about the suffering are all under the challenge and they all will see the outcome of their actions in the hereafter.
Having said that, most of the sufferings in this world are in fact initiated and led by human beings themselves. Only a tiny fraction of these sufferings are due to natural calamities and incidents which may be attributed to God.