You have a good question here , I think that some people will not be honest to admit the truth and say life is not the way they would want it to be
But I can reply to the opposite of the question how has my life change with Christian principles then without it and
has my life improved.
Ps 119:105 Your word is a lamp to my foot, And a light to my roadway.
For me I tested to see was these words true are they realistic to follow.
And I must say nothing is never perfect but
the road in life is clearer,
Heb 5:14 But solid food belongs to mature people, to those who through use have their perceptive powers trained to distinguish both right and wrong.
I learned through use as it is written , many opportunities will have us do the opposite , following what we may feel that is right, but only to find out we are leading our self wrong.
The greatest words I had to learn and still work to keep applying is
Pr 3:6 In all your ways take notice of him, and he himself will make your paths straight.
These words are true.