"Do not conform any longer to the pattern of this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what God's will is--his good, pleasing and perfect will." Romans 12:2
Becoming a Christian means being "transformed." A Christian life isn't about conforming to rules and regulations, many non-Christians view a Christian lifestyle as restrictive, but being a Christian means that you will actually want to live according to God's will. It is a willing lifestyle change, though not always easy.
"For it is by grace you have been saved, through faith--and this not from yourselves, it is the gift of God" Ephesians 2:8
And because it's through grace, the gift of God, then it's not a matter of changing lifestyle in order to be saved, but the change will come as a result of accepting God's gift.