One thing we notice with our kids is they can love the idea of something but not the real thing. Like when we come in from the cold. The kids get very excited about hot chocolate. But often they don't finish their hot chocolate. They get excited about the idea of having it but once they have it the reality is not as exciting. People talk about the same thing with stock markets. The saying is the market goes up on anticipation and down on realization. So if there are reports Apple Computer is going to post great numbers their stock will go up. Once the numbers are published the stock often goes down. The idea of higher numbers is exciting. The reality is they are just numbers.
There is the idea and the reality of being a Christian as well. People like the idea of going to heaven. They like the idea of living a moral life. They like the idea of being part of something big like the Kingdom of God. But the reality is sometimes not as exciting. Heaven means being close to God. People say they want to go to heaven. Then you ask them what they can do to get close to God. They answer with things like reading the bible, praying, going to church, etc. But do they do those things? Often the answer is No. So they like the idea of heaven but do they like the reality?
This distinction really creates problem if you believe in "faith alone." How do you know the person has not just accepted the idea of Jesus and not the reality? The truth is there are many idea about who Jesus is. It is only when somebody grows in holiness that they understand the true Jesus. You say Yes to the idea but more and more your Yes becomes a Yes to the reality. So Catholics believe God gives you a choice every step of the way. If you find the road to heaven is too hard and you prefer the things of this world God will not force you. But it is a problem if you want to say everything depends on the initial Yes. Because that initial Yes can be based on a very shallow and even a very wrong idea about Jesus.
So if someone says Yes to Jesus based on a "health and wealth" gospel does that save him? If he rejects a more orthodox gospel does that matter? Or maybe someone accepts a gospel that is quite liberal on question of sexual morality. Many people will start there and grow into the fullness of the faith. You can see they really did fall in love with Jesus and it was only a matter of time before they surrendered themselves to the true gospel. But then there are others that don't follow Jesus when he asks them to surrender the hardest areas of their lives. Their initial Yes looks exactly the same.
So protestants go in two directions. They both lead to real problems. One group talks about how just accepting Jesus is all that matters. They would take that initial Yes as always leading to eternal salvation no matter how flawed the person's notion of the gospel might be. Now if you scratch them they will admit some boundaries. Leaving the content of the gospel wide open is pretty untenable. But even if you did you get another problem. Why should we preach the true gospel? Get people to say Yes to Jesus anyway you can. Just get them saved and move on to the next person. But that is not what Jesus did. He made sure they understood the true gospel and how hard the path to holiness really is. So you end up with a strategy for evangelism that is, by your thinking, much better than the strategy Jesus used and the strategy most Christians have used throughout church history.
Then there is the other direction. To assert some sort of reasonableness to the gospel that a person accepts. The idea of a baseline Christianity of certain doctrines people need to get right for the Yes to count as salvific. But there are huge problems there too. First of all, there is nothing like that in scripture. Secondly, people disagree wildly on what should be a baseline doctrine. It leads you into the endless subjectivity that can never be resolved because principle of a resolver is rejected. Requiring any content at all to the faith means you require a definition of that content. A definition, in turn, requires a definer.