"所谓的不信郁金香就不得救，就是一种必须靠自己的好行为"

You know not what you are talking about at all!

First of all

you should figure out the expression of 

不信郁金香就不得救 

really want to express what idea or opinion,

郁金香

because it summarized the redemptive salvation

precisely unambigiously harmaniously,

we can simply say 郁金香= Jesus' redemptive salvation,

thus, if anybody believe not Jesus' redemptive salvation,

where s/he would go????? crystal clear!!!!!! isn't it???????!!!!!!!

no matter clear it is, personally,

I don't encourage brothers and sisters to use that expression 

since this expression is often  twisted into something else

not only by those who understand not 郁金香

but also by who who, like you, understand 郁金香.

This expression has nothing to do with 靠自己的好行为 ,

since it really the same as another expression 

 不信Jesus就不得救, 

不信Jesus' redemptive salvation就不得救