How do we know God is for us? He gave us Christ! Christ who suffered for us and entered into our own suffering so that we may have a deeper union with God. 

For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.

Romans 8:38-39