That website seems to have a fascination with Hollywood, Esotericism, and Protestantism. It is also amateurish. Paul Johnson was not an Oxford University church historian but a conservative writer for a popular (general) audience. Ian Paisley was a fundamentalist preacher turned politician, not a serious scholar. At a glance, the quotations from Church Fathers about the Septuagint and Gospels seemed authentic. The problem is that you will get so much non-Orthodox propaganda on this site and the attempts to give the Orthodox perspective are not especially learned or intelligent.
I will probably be criticized for this, but I still believe that Timothy Ware's section on doctrine on his book The Orthodox Church can be very useful. His section on the Fall and ancestral sin is very informative. It can help one differentiate Orthodoxy from western approaches. He is completely wrong on ecumenism and some historical issues. Also recommended is Father Michael Azkoul's Teachings of the Holy Orthodox Faith and the writings of Saint Justin Popovich. Father Michael Pomazansky's book is useful as well. At an advanced theological level, everyone needs to read Saint John of Damascus's Exact Exposition of the Orthodox Faith.
If you want to learn about Orthodox apologetics, first set aside the Protestant questions and read ORIGINAL ORTHODOX TEXTS: the doctrinal definitions of the Seven Councils, Photius, 1285, Palamas, Synodicon of Orthodoxy, even Jeremias and Dositheus (who were not perfect, but very useful). Most of these ORIGINAL ORTHODOX TEXTS are online, and some have been posted here. If a website is sensationalist or focuses on responding to Protestant arguments, it is probably a distraction. Protestantism is a new religion invented 15 centuries after Christ. The more ORIGINAL ORTHODOX TEXTS that you absorb, the more Protestant debates will seem ridiculous.
Lastly, a great way to learn theology is to read Matins in the 12-volume Menaion. It summarizes the theology of the Church in a pious and prayerful way. LEX ORANDI, LEX CREDENDI