There are endless debates about how public one's faith should be. Should we keep it behind closed doors, or should we be as obviously Christian as is humanly possible? Is Jesus really against public prayer? Is faith really something we should just keep to ourselves and share only if asked?
The debate can be settled very easily with one word: context. You can take the Bible and make it say just about anything you want. It's just an unfortunate side effect of language: Words can be twisted, particularly when you are selective in quoting them. The Bible does talk about private faith, praying behind closed doors, and doing works in secret. But it also talks about open faith, praying publicly, and doing works to be seen. So which is it? Both. There is no contradiction when you realise that the motive changes the morality.
The whole point of the Christian faith is to glorify God. Faith is not supposed to draw attention to you, but to God. So stop and ask yourself "why am I doing this?" If you're loudly announcing to the world "look at me! I'm doing something good!" and they suddenly start thinking "wow, what a wonderful man!", you're doing something wrong. But what if you're quietly announcing "this is for you, Lord"? What if, rather than making it obvious how "great" you are, you boldly proclaim how great God is, and you show it by being good? Thus, the difference isn't between public and private faith, but between whether or not they see you or Jesus.
Interestingly, we have an excellent example of this in Moses. In Numbers 20, Moses is commanded to speak to a rock before the eyes of the entire Israelite community in order to make water come out. Moses responded by speaking not to the rock, but to the people, saying "Hear now, you rebels! Must we bring water for you out of this rock?" (v10), before striking it twice with his rod. The result was the same. Water poured out of the rock, and Israel was filled. But God was not happy, telling Moses "Because you did not believe Me, to hallow Me in the eyes of the children of Israel, therefore you shall not bring this assembly into the land which I have given them." (v12).
Moses was commanded to do a thing in public in order to bring glory to the Lord. Instead, He chose to take the glory for himself. Notice the visibility of the act is not what mattered here. Moses was actually commanded to gather the congregation to see this. What mattered was who got the glory for it.
God is never content to stay in the background while we take center stage. As Christians, everything we do should either involve looking at Him ourselves, or pointing others to Him. Sometimes, that does involve closed doors. But you're a Christian first and anything, everything else second. That really can't stay hidden for long. So shine like a spotlight.