Shiva, Vishnu,Brahma,Christ or Allah and all their manifestations are just interpretations of the ONE and the INFINITE whom we refer to as God. There is no need to feel torn between our devotion to Shiva and Vishnu. Whatever path of devotion you choose you shall meet GOD on your day of judgement. It is best to see God in our surroundings and in our deeds. So do no great things only small things with great care.