Perhaps, we should think before we say something or giving idea in the public. I was stunned by the statement saying that Christian practices immorality by celebrating Valentine Day. What St. Valentine has done is nothing to do with Islam in whole. In fact, Christianity teaches love, harmony, peace and self-sufficient and Islam does.
I think, we should respect each other by keeping our excitement or obsession towards our religion value and understanding so that we may not insult other people. We should keep the golden rule in our heart ; "Do not do to the other what you would not like them to do to you."
There is no need to have a debate on religion issue as we have agreed to respect each other and no end or solution for any misunderstanding within Islam and Christianity. If we able to talk openly about the other religion weaknesses or the their bad things then we should make our self prepared to be the best among the rest. And not by insulting other people or accusing other religion for practicing their faith. I am not saying that Valentine day is a Christian celebration and church has never highlights valentine day or St. Valentine in their teaching.