Maintaining respect to their previous faith while explaining Buddhism to a person who is in another school of Buddhism or another religion? I have a Blog and a lot of people come to learn Buddhism in it. I want to start doing articles on Theravada Buddhism and i do not have any idea if i can do it without being a bit corrosive in certain topics.
I want some advice how to do this.

So can you guys help me?
It is most honorable to do whatever you can so that people who take what you give take it smoothly. However, what you can do in this area is limited.

To paraphrase Lama Tsongkhapa, if he who receives what you give is like a vessel turned upside down (not open to listen, to receive) nothing will enter; If he is like a leaking vessel (forgetful, not paying attention), whatever will enter will not remain; If he is like a dirty vessel (having a faulty motivation) the pure nectar you will pour in by way of teaching the Dharma will turn to mud.

However, there are things you can do to make sure people listen to you with an open mind. For instance, one is likely to be open if you are an example. If a beggar was to tell me the same thing my teacher tells me, it would not sink in in the same way because I would not  be as open as I am in relation to my teacher. This is because I have more respect to my teacher, I trust him and I trust his words, his guidance, his intentions. Therefore, that your reader trust you is important. If he does not trust you, his ears will be closed. And in order to be trusted, you have to be trustworthy, you have to be exemplar, for instance in showing respect for others and other traditions. Maybe you can include Links to websites of other traditions on your blog, as a sign of openness, and interest from your part.

Moreover, I noticed that in the West, many people prefer being told that "it is a method, it is a practice, it is a path among many others, and it works in this and that way" as opposed to "it is the truth". We like being right, we hate being wrong, we dislike being proven wrong. So, if you emphasize (1) the practical aspects and (2) contexts, that might help not dwelling to much on the 'right or wrong' type of approach.

Finally, I visited my teacher recently. I also, tend to be a bit corrosive with regard certain topics and debating with him showed me that it was due to my own pride, my own arrogance. It's always the "I know, others do not" tendency, or the "How could anyone even think in this or that way?" tendency that tends to take over. If you reduce your pride, you will naturally be smoother and more respectful.