Why do Christians play God...........?

and interfere with His Will by trying to extend their lives on Earth, when God is calling them to Heaven? After all, the opposite, euthanasia and suicide is a sin. Where in the Bible does it say that anyone but God can make that decision either way, life or death? Shouldn’t a true Christian have faith in their God that if someone falls sick and is dying that it's God’s will? I have heard Christians say, that after someone dies "that it was God's Will". Eternal life awaits, why delay? Why do Christians cling to this life, even when in constant pain and suffering? Do they not trust in God's Will and resort to medicine? God does not need medicine to heal someone if He really wanted them to live. Where is there faith, why do they go to doctors first? Why is a Christian funeral usually depressing, they should rejoice in the liberation of their loved one? Yet they still wail and cry. Seems counter intuitive if one really believes their own stuff.