Great question. Thanks for asking. I'll give you my answer, and if you want to discuss any part of it, please, let's do that.

In a sense your sister is right: If someone gives their life to God, God saves them. I find that's a bit of a simplistic answer, though, the way the world is now. Sixty years ago when Bill Bright wrote the Four Spiritual Laws and they were so successful, American culture still sat on the foundation of Christianity. Most people went to church; most people had some understanding of the Bible; most people believed in God or would say there is a God, even if they didn't believe. We are [i]WAY[/i] far away from that now, and usually people now need to have some knowledge put in on top of "God loves you" top have a real understanding of what they are committing to.

I recently surveyed the Gospels to make a list, from the mouth of Jesus, as to how you get into Heaven. What is it that gets you there? Jesus gave many answers, but a cluster of them rose to the top via repetition:

[list][*] If you want to be part of the kingdom of God, you must repent and believe. Sin is presented as the antithesis of Jesus and it must be repented from.
[*] That Jesus Himself is the access point, and Jesus is calling sinners to himself
[*] That one must be born of the Spirit
[*] He is looking for faith.
[*] Obey the Law and keep the commandments (here's where the two commands are applicable).
[*] Do God's will
[*] Put the words of Jesus into practice
[*] Align yourself with Jesus, identify with him, and follow Him
[*] Love God
[*] Love Jesus
[*] Lose your life (deny self) for Jesus's sake
[*] good works ("love of neighbor")
[*] Humility
[*] Live by the truth; come into the light, both of which are Jesus Himself
[*] Drink the "living water" that Jesus gives[/list]

I would summarize it this way: Repent of your sins and align yourself with Jesus. Come to Jesus, believe in Jesus and follow him—put his words into practice, love him, allegiance. Follow him, identify with him, and learn from him.

See, people used to know this and understand it as what was involved in responding to God's love with faith. Nowadays people [i]don't[/i] know these things at all, and some information and understanding is essential to accepting God's free gift.

I've talked to people who don't recognize that God is even possible, let alone loving. They say there is no such thing as sin. They say Christ's death on the cross was nonsense and can't possibly save—that it wasn't even a sacrifice. You can read these conversations here on the website. Just to tell someone "God loves you" and they accept His gift is a GREAT summary of what's going on, and there's nothing untrue about it, but in our world, just like in the minds of Jesus's hearers, more was needed. Jesus didn't just give a simple message—the same message to every audience. He explained and taught the concept of salvation from many different angles. We don't want to make it too complex, but neither do we assume it can be simplistic.

Recently I had a discussion about salvation with my sister about salvation. She was on staff at Campus Crusade at one point. We got to talking about salvation as it relates to people who are living in sin. Part of the problem I had with what she had to say is that she basically thinks that it is enough to tell someone that God loves them and if they accept His gift then that is good enough. The problem I see is that in our culture - what if the person has a sinful part of their life that they dont want to give up and wont (something like living with someone or even is married to someone of the same sex etc...) What do you tell them about their sin / putting God in charge of you life (basically repentance)? I think that was the whole point of the parable of the rich young ruler. Jesus told him what he had to get rid of that was causing him not to put Jesus in charge of his life. To me its either missing the point or at best a bait and switch by telling them later what it takes to be saved.