Socrates, Plato, and Aristotle have historically been revered as great intellectual minds among Christians.
St. Justin Martyr, a Christian theologian and philosopher of the mid 2nd century, regards Socrates nearly a pre-Christian saint among the Greeks.
Plato's philosophy was important to many early Christian thinkers, such as Origen of Alexandria, and includes also St. Augustine of Hippo who applied Platonic and Neo-Platonic philosophy to Christian theology, trying to assimilate the best of the Platonic tradition. And Augustine remained the preeminent theologian of the Western Church into the middle ages.
With the re-introduction of Aristotle's philosophy into Western Europe through interaction with the Arab world, Aristotle became incredibly important to the scholars, philosophers, and theologians of the high middle ages, in particular through the works of St. Thomas Aquinas. Aquinas became the theologian of Western Christianity in the high middle ages and for Roman Catholicism generally remains so. The Roman Catholic doctrine of Transubstantiation is Thomist in articulation, and is rooted in the Aristotelian definitions of substantia and accidentia.
The pre-Socratics, such as Heraclitus and Zeno, were instrumental in establishing the philosophical language of the Logos, which is adopted into the philosophy of the Jewish Platonic philosopher Philo of Alexandria, which is the linguistic background for the Logos language of St. John's Gospel, "In the beginning was the Logos, and the Logos was with God, and the Logos was God." And the identification of Jesus with the Logos is made possible because of an established Greek Logos tradition in the philosophy of the Greeks going back to Heraclitus and the Stoics.
St. Basil the Great, one of the most important theologians of the Church in the 4th century, taught his students to be "wise honey bees, choosing only the choicest nectar" meaning to take the very best of the Greek thinkers, but not embrace everything uncritically.
So I'd say the Greek philosophers are an invaluable resource, that doesn't mean to accept them uncritically in everything--there's certainly plenty in the philosophy of Plato or Zeno that shouldn't be accepted--but when they are good and helpful, they are good and helpful.
And of course Socrates' statement that Apollo named him the wisest man in all of Greece because, "The only thing I know is that I don't know anything." is a fantastic bit of wisdom that should sober every thinking mind.
-CryptoLutheran