The thing about Christianity is that you can always be forgiven. It's understood that people are imperfect sinners and while there are ideals and moral codes, we will fall short of them.
Sure, but there is all the stuff about how not everyone who worships Jesus will join him in heaven and there is the parable of the sheep and the goats.
One of the parts you are thinking of is Matthew 7:13-23 [1]. The interesting thing about that is that people who are trying to do the things that Christians do are the ones that are not accepted. So yes, you literally cannot do things good enough, those guys performing miracles weren't good enough.
The only way to do things good enough is to, for lack of a better term, seek after Jesus. And then he works in your life, and that's the only way to "do the will of the Father". There are specific verses for all that, but to keep it short (and encouraging), just look up a few verses to Matthew 7:7-8 [2] "Ask, and it will be given to you; seek, and you will find"
One of my favorite things about Christianity is that even in this time with all of our knowledge and access to everything it is so widely misunderstood, in almost all of its principles people have almost the opposite conclusion from what was intended. It's fun to explain it, if I can assume I understood it correctly ;)