The Dutch are not increasingly secular according to this interesting piece from Joshua Livestro in the Weekly Standard, rather secularization in the lowlands peaked in the 1990s and faith is making a steady comeback, albeit in a different format:

Apart from being a herald of potential change from secular to post-secular society, youth churches are also an indicator of another significant development, namely the move away from the church of bricks and mortar to a less clearly recognizable, more informal setting. Youth churches seem to meet anywhere but in traditional church buildings: cultural centers, sports halls, school assembly rooms, parking lots, even in night clubs. The idea is that something that less resembles a traditional church might prove more welcoming to potential new believers.

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The question, though, is whether Christianity is best placed to profit from this development. For better or for worse, Dutch Christianity is now largely an underground phenomenon. If an average Dutchman has any picture of Christianity, it is of empty pews and derelict church buildings.

As with the impending demographic bust, the jury is still out on this particular phenomenon and it may be a while before we can confidently claim that secularization was a late 20th century fluke.

There are however a number of remarkable indicators that God is not exactly ‘out’. As Livestro notes, for all the Muslim immigrants arriving in The Netherlands there is also a significant Christian influx - think of the droves of Catholic Poles for instance – that contribute to this phenomenon. Furthermore, during the last general election, the parties with a Christian background did surprisingly well, the small Christian Union will for the first time in its history form part of a coalition government. And lastly, I do think there is a natural tendency in atheist and individualistic western societies to somehow re-connect with spirituality and community. The question of course is if that urge is channeled in the right direction as I can think of many other houses of worship that would make continued secularization a far more preferable option.

Islam however is according to Livestro not all that well-positioned:

Even the most optimistic estimates of Dutch Muslim organizations put the number of converts to Islam at no more than a few hundred a year. With immigration from Islamic countries grinding to a halt and birth rates among the Muslim community further approximating average Dutch birthrates with each new generation, it seems unlikely to say the least that visions of a caliphate in Holland will come to pass in this century--or the next, for that matter.

Speculation of course, but the notion that birth rates will overtime fall into line with the local breeding rate – often a function of economics – is correct as noted here and here before.