“For it is by grace you have been saved, through faith (Eph. 2:8a).” No matter how you understand faith, it is clear that it is instrumental in our salvation; we will not be saved without it. But what is this faith that plays a part in our salvation? Hebrews 11 tells us that there are two aspect to faith. It is believing in something. And it is acting on that belief.
And John makes it clear that God loves the world. Not just some people who are in the world. But he has a love for everyone. And Jesus came to be the savior of everyone. And all who will believe in him will experience that salvation he offers. Those who refuse to believe will remain in this world and be condemned.