For sin will not rule over you, because you are not under law but under grace.
What then? Should we sin because we are not under law but under grace? Absolutely not! Don’t you know that if you offer yourselves to someone as obedient slaves, you are slaves of that one you obey—either of sin leading to death or of obedience leading to righteousness?
Romans 6:14-16 HCSB
By the grace of God we are saved, not by any works of man. We have salvation when we choose to accept Jesus Christ as our Lord and Saviour; when we are obedient to His directions in the accepting of our Gift. When we accept the Gift of Salvation from the Lord, the Gift He paid for in His blood, we are to show our obedience to Him, not to the prince of this world.
We only have two masters to choose from, satan or God; you have free choice to follow whichever one is before you; but be careful in which one you choose, because one leads to death, and the other to life.