Every Christian (person born again of the Holy Spirit) will be saved. The gift of the Holy Spirit is the guarantee of salvation (Eph 1:13-14).
The difference between a dedicated Christian and a "pew-warmer on Christmas and Easter" Christian will be rewards. Dedicated Christians will receive a "rich welcome" (Heb 10:35; 2 Pet 1:11; more..), lazy Christians may get nothing at all (1 Cor 3:10-15). But every Christian will be saved.
what does it mean God will judge each person according to what they have done?
2 Corinthians 5
For we must all appear before the judgment seat of Christ, that each one may receive his due for the things done in the body, whether good or bad.
seems pretty straightforward, but Paul didn’t really explain what happens to those bad works in 2 Corinthians 5.
However, Paul explained in Romans 2 that works aren’t just rewards. They’re the standard by which we are judged, given eternal life, or receive God’s wrath.
But because of your stubbornness and your unrepentant heart, you are storing up wrath against yourself for the day of God’s wrath
, when his righteous judgment will be revealed.
6God “will repay each person according to what they have done.”
To those who by persistence in doing good seek glory, honor and immortality, he will give eternal life.
But for those who are self-seeking and who reject the truth and follow evil, there will be wrath and anger. 9
There will be trouble and distress for every human being who does evil: first for the Jew, then for the Gentile; 10
but glory, honor and peace for everyone who does good: first for the Jew, then for the Gentile. 11
For God does not show favoritism.