Christianity in the bargain bin

We see in Rick Warren's presentation below an assurance that the listener will enter heaven. But can a person really have such assurance when the message presented is so ambiguous? Is not the sinner's prayer being treated here as something akin to a magic incantation -- repeat the right words, and you're automatically in? What are the possible consequences to the hearer if such an assurance is false?

One thing that strikes me is that Warren's message is so soft, it would be hard to imagine anyone rejecting it (except to dismiss it as mere nonsense). As it's presented, why not pray the prayer? There's nothing to lose. No costs to consider. Just tell Jesus you want to be friends and God will give you a ticket to heaven.

Did Jesus make it that easy?

The Cost of Being a Disciple
Luke 14:25-33

Large crowds were traveling with Jesus, and turning to them he said: "If anyone comes to me and does not hate his father and mother, his wife and children, his brothers and sisters–yes, even his own life–he cannot be my disciple. And anyone who does not carry his cross and follow me cannot be my disciple.

"Suppose one of you wants to build a tower. Will he not first sit down and estimate the cost to see if he has enough money to complete it? For if he lays the foundation and is not able to finish it, everyone who sees it will ridicule him, saying, 'This fellow began to build and was not able to finish.'

"Or suppose a king is about to go to war against another king. Will he not first sit down and consider whether he is able with ten thousand men to oppose the one coming against him with twenty thousand? If he is not able, he will send a delegation while the other is still a long way off and will ask for terms of peace. In the same way, any of you who does not give up everything he has cannot be my disciple."