Exactly, they go by inductive reasoning. Macro evolution must be true, therefore as far as they are concerned, anything that doesn't fit into this conclusion, this paradigm, gets rejected outright. They claim their studies are "peer reviewed", yet this is far from the truth as we have seen them attack people who were once considered colleagues the moment they come out with evidence contradicting the paradigm.
The problem is that evolutionists are very aware of the holes and inconsistencies in the theory, otherwise they would be accepting it as a hard and fast scientific law; so they choose to believe it because they choose not to believe that the universe was created by a divine being, namely God. They deliberately leave God out of the picture, and hold fast to the "religion" of evolutionism.
In essence, they have adopted a version of "faith", in that despite the inconsistencies, they believe that evolution is true. Because there is no other explanation that they are prepared to accept, evolution is the only possibility for them.
At one stage in human history, truth was objective, and because the scientists of the time did believe that God created the universe, their investigations and discoveries were on that basis. But at some stage during the Enlightenment, philosophy concerning "truth" changed. It changed from truth being truth because it is truth in the objective sense, to "truth being what we believe to be true". Therefore truth ceased being and object in itself, and became dependent on whether the individual believed it or not.
So, for the individual who does not believe in evolution, it is not truth for him, and the individual who does believe in evolution, it is certainly truth for him and he will defend it until the cows come home.
It is the same for some interpreting the Bible. Those who believe that the Bible is objective, literal truth, it is truth for them. For me, the literal Bible is objective truth whether people believe it or not, therefore it is not dependent on personal belief. It is true because it is true.
But some will come up with interpretations of passages of the Bible which they read into a spiritual "sub-text", and it become true for them. These are the ones who will say, "You have your interpretation and I have mine". For example, the minister of the liberal side of my church preached on the woman at the well in John 4. His take on the living water was that it was the living water of tolerance between different religions and cultures. That was what he believed the text was speaking about. But what he was doing was adapting the passage to fit in with his liberal belief, rather than expounding the Scripture to show what it actually says. But he believed his own version, so it was truth for him that this is what Jesus actually meant through His example of a Jew talking with a Samaritan woman, saying that Jesus wasn't selfish in drawing the water himself, but allowed someone of a different culture draw the "living water" of cultural tolerance for Him.
So this is the sort of thing we are up against when debating with atheists and agnostics. They will defend to the last what they believe is truth for them, making them a very hard nut to crack.
By the way, there are Christians who believe in evolution, because they have difficulty getting their heads around that God can create a whole, aged universe in six 24 hour days. So evolution is truth for them. However, whether a person believes in evolution or not, is unessential for true conversion to Christ, because the heart can be right with God, although the head might be nor not be aligned.