This is a great question. There will be many different opinions, but let me give you my take on this.
First, Christians are not supposed to become like the world. There is a call to non-conformation to the world. For example, Paul says in Romans 12:1-3 that Christians are not supposed to conform to the patterns of the world. Hence, Christians are called to create a new culture.
Second, Christians are not called to separate from the world. This point might sound very odd in view of point one. The paradox is resolved in John 17 when Jesus says Christians are supposed to live in the world but not be of the world.
Finally, above all Christians are supposed to be people filled with love for others. 1 Corinthians 13 makes this point very clear.
I wholeheartedly agree with "readerofbooks" that Christians are called to not be "conformed" to a secular world, but to live holy lives honoring God. This does not imply withdrawing from the world (Jesus never withdrew from the world), but rather engage the world in a responsible manner (as Jesus did - and also mixed with prostitues, tax colectors etc). That would include not being judgmental whilst at the same time honestly and without fear putting forward the Christian viewpoint.
To "proselitize" should not really be a problem in view of the fact that the opinion "not to proselitize" is put forward as a view - which is actually "proselitizing" this particular view? It cuts both ways.
We are all born as man and later on divided as Christians, Islams or Hindus etc. we are born in different parts of the world. People practice different religion in different parts of the world becase those religions prevail there. Religions have their own philosophy. People those who like or belive in Christianity become christians. Then why will not be in this world?
You are right that the world is secular and yet we believe in certain religion and think that I am christian or Islam or so on. Besides we feel our religion is the best of all. Every man has the right to practice any religion, its not an offence. But proselitizing makes the difference. People should be left to his desire. The teachings of christianity are not bad but a few who interpret them have ignorance and unable to teach properly. therefore they are busy in increasing numbers of member but not true christian. Thus I think people those who believe in christianity have the equal right to live in this secular world respecting all other religions equally.
People interpret 'sayings' in Bible variously-depending on their depth of faith.Therefore if anyone quotes from Bible inorder to stress a point or two,it needs to be examined independently by the individual who considers himself as a true follower of Lord Jesus Christ.Jesus has given us a lot to think about and follow.Parables in Bible are good indicators. We need to remember that narrow views have never been part of Bible teachings.Is there any other better 'secular' statement other than'LOVE THY NEIGHBOUR'??There are numerous gems scattered allover in the BibleSpoon-feeding in religious matters,whether positive or negative one does hide the true spirit of teachings in Bible.