1. What Do I do to Become a Mature Christian
The simple answer - Scriptural study, prayer, meditation, introspection, and involvement in communities within and outside of your church.
The more complex answer: Some serious soul-searching. You need to experience this world in order to understand why what the scriptures teach is important - it is one thing to say that "the poor are needy, everyone knows that"; it is another to know the needy, understand them, and help them if you can. In understanding this world, there is knowing with your head (which is all well and good), but there is knowing with your heart, which is infinitely better. Experience in debating and discussing all manner of topics with both Christians and non-Christians is vital. Jesus sought those who had not heard the Word, that they might hear it - and you will discover rather quickly that they don't think they want it. The naïve Christian won't understand why a person could possibly reject salvation and the love of God, and consquently blow off the people who most need a kind ear - because listening to people is hard; the mature Christian will try to understand their reasoning, even if there is nothing to be done for them at a certain time. And this is only the tip of the iceberg . . .
2. How Long Does This Take?
There seems to be a "critical mass" of life experience (and/or struggle with external forces) necessary to evolve beyond a naïve interpretation of Christianity. The naïve Christian believes that God does whatever they ask in His own time (if you think of God as a happy bearded man in the sky who's watching your back and thinking about you constantly, this might be a problem); that God's workings are evident by the fact that good things happen when you pray for them (I do not deny the power of prayer - it is a mystery unto itself that is usually not interpretable in words; however, I am a firm believer that "God helps those who help themselves" and that "God works in mysterious ways"); that God "simply must be" (when you take any relationship for granted, the relationship may stagnate and taper off); that bad things don't happen to people who love and fear God (this is most definitely a mistake); finally, a naïve Christian thinks they have a free ticket into Heaven, and knows exactly who's going to Hell ("You can safely assume that you have created God in your image when God hates all of the same people you do" - I don't remember the source of this, unfortunately). Generally, a naïve Christian will take an "I'm right, you're wrong, and God is on my side" approach to an attack on their beliefs and views.
When I talk about "a critical mass of life experience or struggle", I mean this - no relationship can grow until it knows its boundaries. Many Christians treat God as a model fair-weather friend - when everything goes well, God has blessed them; when things go wrong, God has abandoned them, "I don't need God", "God hates me", "What did I do to deserve this?". A relationship with anybody (especially God) can not mature without being tested. In life, we know who our real friends are when everything goes wrong - a similar notion applies to understanding our relationship with God.
A mature Christian attempts to live the fruits of the Spirit; display the aspects of love (as in 1 Corinthians); genuinely attempts to understand and live the "11th commandment" or Golden Rule; accepts that there are certain things they can/may never understand about God, our world and the one beyond, but attempts to understand anyway; empathy and compassion for humanity; the list goes on.
3. What Role, the Sacraments?
I was raised as a Missouri Synod Lutheran (so this advice will specifically not apply to Baptists and Catholics)- this means that I acknowledge two sacraments, communion and baptism. The Koine Greek word, "sakramentos", means "mystery" - and I see the workings of the sacraments themselves as a mystery of faith and trust in the workings of God. There are understandings of the sacraments that come about through study which are deeper than those that come from "take and eat . . . take and drink . . ." - I believe in a confirmation (or catechismal) class to help explain some of the "theory" behind the sacraments.
Too Slow: How slow is slow for God? Don't expect this to happen overnight - most "conversions" to a mature worldview take months or years to gradually become stronger. Consider pray for the patience to accept the results as they come, and the wisdome to see the results when they appear hidden.
4. When All Seems Lost
Stagnating:Talk it out with other people - close friends and local ministry, if possible. Consider praying to God for the wisdom to understand what's happening in your life. Read some new books - although the scriptures are the most important aspect of Christian study, commentaries on the scriptures and journals of Christians attempting to lead a God-pleasing life can be very helpful.
Bonus Question on the Toilet Problem
The problem lies not in man or woman - but in the discipline, politeness and courtesy of our society. The seat should be down with the lid on until somebody needs to use the toilet, and should be replaced when that person is done with it. End of story ;)
This was my response to a series of questions that I found intriguing from the questionofgod community - feel free to comment on it at your leisure, but, also, please be respectful of the opinions and beliefs of others.