Ed, you have presented the issue very nicely. Thank you. What you have shared is not understood by most of the Christian world. That we will be judged by the character of Christ is contrary to what most are teaching. Yet, the parable of the Ten Virgins teaches just that. "The bride" is indeed the church purified when the marriage takes place.....after the "investigative judgment".
The important teaching in the parable is that not all who profess to love and serve God in fact will be a part of that church when Jesus takes His bride home. Many sincerely believe they "believe". But, a profession is not enough. As you have pointed out, those who are allowed into the marriage feast must be properly attired. The dress is a gift from God, His dear Son's righteousness. But, where many err, is in thinking that when they put on this wedding garment, they may do so without first removing their own filthy garments. Many have been taught that the character of Christ will cover unconfessed and unforsaken sins. They are right in one respect. Some sins that are unknown to be sin, will be covered by the blood of Christ. But, there is a condition to this promise. The sinner must be fully surrendered to Jesus and filled with His Spirit. Then, "some" sins that are unknown will be covered and the righteousness of Christ will be sufficient. But, in the parable we find that many professors will not be covered by Christ's righteousness. Any sins known to be sin that remain unconfessed and unforsaken will not be covered. In other words, saving faith will be seen by the deeds of the professing believer.
As cp pointed out, if we assume we understand this parable and leave this matter of which sins will be covered and which sins will not, we shall be in great danger of being in the wrong group of "virgins" and be shut out of the marriage feast. The key, as I see it, is in a correct understanding of the gospel of grace and the "investigative judgment" where the standard of judgment will be the law of God.