Derrick, I read the birthday article from the site you listed. (Did you read the one I listed at the top of this thread? Many of the author's arguments are refuted there.)
While I'm sure you agree with the overall point of the article -- birthday celebrations are condemned by God -- do you truly agree with the arguments he puts forth for it? You have a unique opportunity here. This is an article that you essentially agree with, but that was not written by the Faithful Slave. That means you can read it with a critical eye! You can pick it apart, and NOT agree with all of it, without compromising your beliefs. The chance is yours, take it.
Note that you are able to agree with the overall point, but still recognize some of the fallacies in the defense of it.
For instance, he points out that there are only three birthdays mentioned in the Bible (he counts Job's children's "day" as a birthday). All three saw bad things happen. He concludes that God only provided three examples of birthdays and something bad happened at each, so He must be trying to tell us something. Do you agree with that?
By that reasoning, dog ownership and wearing makeup should also be condemned, since they also are presented in a negative light. Do you think dogs and makeup are bad? If not, why not? (Note that makeup has pagan origins, rooted in protecting the wearer from evil spirits.)
The author says that none of the birth dates of the servants of God are known, God saw no need to record them. Why would He leave them out, unless they were unimportant? We also have no record of Noah wearing shoes, Jesus telling his mother "I love you", or the Apostle Paul paying for food. Would all of these activities be similarly condemned? If not, why not?
The author mentions that several Bible writers spoke ill of the day of their birth, similar to the way people might say, "I wish I'd never been born!" If God's word presents the day of one's birth so badly, he reasons, why would it be a time for celebration? On that basis, do you think baby showers should also be condemned? If not, why not?
Much of his argument is based on what the Bible DOESN'T say. The Bible never mentions a servant of God celebrating his birthday. But he fails to mention that the Jews simply didn't celebrate birthdays, it wasn't part of their culture. Canadians celebrate "Boxing Day" -- Americans don't. Should someone conclude then that Americans are opposed to Boxing Day, that we have a religious objection to it? No, it's simply not a part of our culture. What basis is there for concluding that the Bible characters avoided birthdays for religious reasons?
Lastly, be careful not to let him get away with stacking up arguments and trying to win on the basis of having lots of them. People do this at times, especially if their position is weak. They make many poorly supported arguments, then when you shoot one of them down they say, "Well, you may not agree with that point, but I've made 10 points here." Since you can't simultaneously argue all 10 points, they can always lean on the 9 you aren't shooting down at the moment. The trick is to take one point, decide if it's reasonable and supported or not, then move on. When you're done, you only consider the well-supported points. If none of them are supported, then there is no argument at all.
In the spirit of 1 Peter 3:16, your responses would be appreciated.