Hello Susan,
First, let me start by thanking you for sending me your question.
The way I perceive your question is that you have it formulated in a specific way, (perhaps by habit or intentionally) that is reminiscent of some nominally Christian churches I have come across.
Now, I don't know much about your background but I'm aware some denominations put special emphasis on the idea that what's important is to develop a 'personal relationship with God'.
Being Christian means different things to each Christian. We all have our unique expression of godliness and creativity. We have our self, which coincides with the universal human body, in spirit.
We are made in the image of the Creator. Seeing that it is implied that with a Creator comes the object of Creation and the act of creating, if we are made to be in his likeness, we also are and do what "He" does... In the beginning, there was the word. *In french it said this way: "In the beginning was the verb"
The essential principles are commonly understood by most creative and intellectually active people. Love thy neighbour. Forgive. Go out and multiply. Do good. Agape, Love.
To properly and specifically understand what I mean by the word 'creativity' I can only refer you to the works of Lyndon H. LaRouche Jr. as his use of the word reflects my own.
I suggest two avenues for you to get to know more about Lyndon's conception of Christianity.
There's the book "The Science of Christian Economy: and other prison writings"
There's also an article title "On the Subject of God"
Now, to answer your question " why so many Christian pastors and theologians consider humanism a bad thing?" I am suspicious of anyone who considers 'humanism' a bad thing.
I also recall that a special 1992 Gerry Rose presentation which I have recently rewatched in which he mentions the Aristotelean influence on both the Reformation movement and the Counter-Reformation movement. Not only that, but the Aristoteleans' dirty operations are said to have influenced prophet Mohammed.
Perhaps it all makes sense when young Muslim Men tell me that they are warned against studying the works of the Greek philosophers.
It stinks.
A real Christian is a humanist. Or else we come to know them by their rotten fruit.
Have fun!