The last part of the conclusion is a wordy way of saying what was said earlier:
“For even if we give up the entire Bible, Christianity remains.”
This is typical of the pseudo-intellectual clap-trap that says the Word of God is subservient to a hierarchy instead of the reverse.
No it isn’t. He is saying that Christianity survives because Christ survives. He is also stating that if you have trouble defending the Bible against those with minds like Dawkins, then maybe you should try defending the movement that produced the Bible as proof of Christ instead.
You probably also have a problem with the statement that the blood of the martyrs is the seed of the Church. After all there is more credit given to the blood of the Saints for building the church than the word of God.