Why do follow up?

Y' know... it's funny how follow up works. Its like this :
- we say and believe that the gospel is powerful to change even the worst of sinner (e.g. ourselves)
- we say and believe that the Gospel is from God and that God is all mighty and powerful
- we say and believe that this ministry is God's
- we say and believe that once God grab a hold of our hand, no one can ever take us away from Him

We say we believe all these but we say that we need to do special follow up for the people that had just believed in the Gospel. It contradicts each other (to me anyway). Did anywhere in the Bible ever says that we have to do follow up for new Christians? I know the Bible always reminds us to encourage, love, look after, care and rebuke one another (and all that), but i've never seen the world "follow- up" a believer even ONCE in my whole entire life of reading a Bible. 

I think - following up a believer actually have the danger of making Christians to think that it is within OUR power to make someone grow. That it is within OUR power that the new convert will stay a convert. Paul says in 1Cor 3:5-9:

"5 What then is Apollos? What is Paul? Servants through whom you believed, as the Lord assigned to each. 6 I planted, Apollos watered, but God gave the growth. 7 So neither he who plants nor he who waters is anything, but only God who gives the growth. 8 He who plants and he who waters are one, and each will receive his wages according to his labor. 9 For we are God's fellow workers. You are God's field, God's building."

My understanding of follow up is that we specifically set a time to nurture new converts- making sure that the "baby" is secure and growing. But how long should we do this for? How about the old-believer? Does this means that we are no more of importance because we're old converts? What about the church? What part does the church play in follow up? How many people should do the follow-up? etc2. 

My point is... follow-up, in a very subtle way, undermines the power of the Gospel. Follow up gives us the idea that it is ME who is responsible for this, no one else. Follow up simply is full of loopholes. Follow up takes away the joy of believers and gives believers burden when sharing the gospel - because of the consequences that follows. 

So, how then should we look after new believer (i hear myself asking). 

The best and only way we can look after new believers is to live out your FAITH. Faith calls us to be loving, kind, encouraging, always building each other up, rebuking, etc. It's all part of the deal of being a Christian! No one (who is a true Christian) can ever possibliy say that they're a Christian and not be sensitive and loving to new converts. The best way to teach a new believer how to grow is to SHOW them how to grow! To show them how to live out their faith! To pray and let God do the growing job. It's simple, easy and effective. 

If we say that the Gospel have the power to change a person - the TRULY BELIEVE IN WHAT WE SAY. Or else we'll be a hypocrite!