No its not, Christianity and Catholic have many huge differences. Just because they both believe in God, doesn't mean they're the same.
Just for clarification, um you do realize that when you translate Catholic from latin you get Christian, right? I believe your argument applies to Christianity vs Islam, but not versus Catholocism...
Anyways, there are three main difference between Protestants and Catholics, though none of which directly prevent the other from going to heaven, except one that could be detrimental to protestants...
1. There are around five books that are in the Catholic Bible that are not in a Protestant on. If those books were really God's word, then Luther just gave himself a one-way ticket to somewhere he didn't want to go...
2. Protestants believe in the priesthood of all believers. Personally I agree with this concept. The Great Commission seems to support this.
3. Catholics believe in a system of prayer that involves the Saints. I personally have nothing against the Saints and if God decides to use you, I think you should be remembered. As a protestant myself, I only understand that which my Catholic friends convey and some simple deductive reasoning on my part. To my understanding, the point of praying to a saint, is not to worship them but because God has obviously used them, they must be close to Him. That means that if you pray to a saint, then they would act sort-of like a mediator between yourself and God, and thus would be more likely than yourself to have God do what you request.
Personally, I don't believe this is the correct way as it looks as though God is picking favorites. I will not however say for sure. Until God/Michael/Gabriel/other significant angel/saint comes and gives me a direct answer, I won't say that X IS WRONG!!! Because I don't know for sure. I know what I believe, but I don't know for absolute sureness. Sure I'm arrogant and rarely declare that I am wrong, but theology is such a messy grey area that I'm not one to say, "Here's the line." Now, as a Christian, I don't believe that those who practice Judaism/Islam are getting into heaven, but those who do claim to serve God and do it in much the same way I do, may just be more right than I am...
Oh, and one last thing, for the record, these things may seem huge, but aside from 5 books, the difference is very subtle outside a church's doors. Both Protestants and Catholics act very similarly and as about half of my friends are each, I oftentimes can't tell the difference until they are directly asked.
