The Bible truth I want to preach to people is “believe in Jesus for a moment (John 3:14,15) and you are saved forever” —you are forgiven of all your sins—past, present and future (Colossians 2:13), you are sealed by the Holy Spirit (Ephesians1:13-14), you have ETERNAL life (John 3:36), you are justified by God (Romans 5:1), you are irrevocably saved forever (Romans 11:29), and you are destined for Heaven (John 14:2; Philippians 3:20).
Of course, there might be chastisement, loss of rewards in Heaven, and a difficult life because of your sins but it will not result in loss of salvation no matter what, whether you sin a lot or whether you are a great disciple and follower. Salvation is a free gift. (Romans 5:15)
The Jesus you must believe in is the sinless Son of God, the God-man, who lived a perfect life, shed His blood and died for all of your sins on the cross, according to the Scriptures, was buried, and rose again from the dead on the third day according to the Scriptures.
After you are saved, it is God’s will that you live by His love, His grace, by faith, and by His Spirit—but this is not a requirement or a proof of salvation.