Absolutely our lives must be changed. There is, as James 2 points out, a difference between belief and faith. Even the demons believe (in) God, and yet obviously and certainly they are not "saved". They are not saved because, in spite of their knowledge and belief, they do not submit to God and obey Him. This is in contrast to what James says faith is- belief working itself out in love. There are waaay too many "Christians" who believe that when Christ's righteousness is imputed to us, that means we get the benefits without the work! Christ's righteousness imputed to us means God enables us to be righteous like He is. We are not just
called righteous, we are
conformed to His righteousness. There is a big difference between the two.
Glad you are here and welcome to CC