God's love and justice are not irreconcilable. The truth is that God hates sin and all humans are sinful. God's justice demands that his wrath and judgement come down on sin. This is a very scary thing. In fact, while talking about God's judgement, one Biblical author said "It is a dreadful thing to fall into the hands of the living God." (Hebrews 10:31). God is angry at sin and his wrath is coming. This is a reality that is not popular in our world, but it is nonetheless true.
However, God also loves us and wants a relationship with us. He is not a malicious God. God does not like it when people reject him and suffer his wrath. God says in Ezekiel 18:23 "Do I take any pleasure in the death of the wicked? declares the Sovereign LORD. Rather, am I not pleased when they turn from their ways and live?" God doesn't want people to turn from him and die. He wants people to have life. That's why Jesus came on cross and died for our sin. Because Jesus lived a sinless life and died on the cross, he was able to divert God's fury, wrath, and judgement from sinners onto himself.
That's the reason people need to believe and follow Jesus. Anyone who has accepted Jesus as their Lord and Savior is no longer guilty. They have the righteousness of Jesus; this doesn't mean they don't sin, but that their sin is forgiven and God has given them new life so they can fight sin and become pure. However, anyone who rejects Jesus and does not follow him faces the reality of God's wrath and judgement.
This is the gospel: "Christ died for sins once for all, the righteous (Jesus) for the unrighteous (you and me), to bring you to God." (1 Peter 3:18)
The most important decision people make in their life, even if they neglect to make it, is whether or not they will worship Jesus.
