Now that I'm a Christian, how do I avoid slipping into my old lifestyle habits?
When we repent of our sins and by faith receive Jesus Christ as our Savior and Lord, we receive Christ's righteousness (Romans 3:22-24). God now sees Christ's righteousness in us rather than our sinfulness. Our sins are forgiven, and we are made right with God (John 1:12).
Now God calls us to love and honor Him as Lord of our daily lives. To do this, we must surrender every area of our lives to His control, allowing God to make us more like His Son (Galatians 2:20).
After receiving Christ, there is a real danger of slipping back into old sinful ways. The solution is to commit each day to the Lord and share our problems with Him. We must give Him authority over our lives, confess any known sin to Him, and receive His forgiveness as promised in 1 John 1:9.
Our victory has already been won for us by Christ's death and resurrection; see 1 Corinthians 15:57-58. It is now our responsibility, with the help of the Holy Spirit, to live in that victory by practicing biblical standards of behavior as noted in Ephesians 4:22-32.
It is tremendously important that we daily meditate on the Word of God, obey His instructions, continue regularly in prayer, and fellowship with other believers in a gospel-preaching church. As we do this, we will become mature Christians, established and strengthened in Christ; see Romans 5:1.