The Publican and the Pharisee
Question: "Christ gave a parable about the Pharisee and how he fasts twice a week (Luke 18:12). Why did the Orthodox adopt things Christ condemned in Scripture?"
Nowhere in that passage does it suggest that Christ condemned the Pharisee because he fasted twice a week. What is condemned is his boasting, and his judging himself to be better than the publican. In Matthew 23:23, Christ said: "Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier matters of the law, judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone." Note that while Christ clearly indicates that tithing the mint, anise, and cummin was of lesser importance than the weightier matters of the law, He nevertheless says that they should have done the former without omitting the latter... not that they should have blown off the tithing of these things.
We begin our preparation for Lent with the Sunday of the Publican and Pharisee, and in fact, in the following week we do not fast on Wednesday and Friday to drive home the point that humility is more important than fasting. But in that service, we clearly acknowledge that the good things that the Pharisee was doing were good in and of themselves, and worthy of emulation, but we should reject his pride:
"Let us make haste to follow the Pharisee in his virtues and to emulate the Publican in his humility, and let us hate what is wrong in each of them: foolish pride and the defilement of transgressions" (Lenten Triodion, Sunday of the Publican and Pharisee, Canon at Matins, Ode 5, first troparion).
In Matthew 9:14, were are told that St. John the Baptists disciples asked Christ: "Why do we and the Pharisees fast oft, but thy disciples fast not?" Christ did not use this occasion to denounce fasting. He instead explained why His disciples were not fasting at that time, by asking them the question: "Can the children of the bridechamber mourn, as long as the bridegroom is with them?" But he went on to say: "...but the days will come, when the bridegroom shall be taken from them, and then shall they fast." And so ever since the time of Christ's ascension into heaven fasting has been an important part of the Church's life. Fasting on Wednesday and Friday is apostolic in origin. It is recording in the Didache (8:1), which was a first century record of Apostolic Teaching.
Canon 69 of the Holy Apostles (which was affirmed by the Ecumenical Councils) states:
"If any Bishop, or Presbyter, or Deacon, or Subdeacon, or Reader, or Chanter fails to fast throughout the forty days of Holy Lent, or on Wednesday, or on Friday, let him be deposed from office. Unless he has been prevented from doing so by reason of bodily illness. If, on the other hand, a layman fail to do so, let him be excommunicated."
So clearly fasting is important, but it is important as a spiritual discipline, and is a means to an end -- not an end in itself. It teaches us to say "no" to our desires, which is a skill that comes in handy throughout our life. It is also a matter of obedience to the Church, and of entering into periods of fervent prayer with the whole Church. However, if we fast, but allow ourselves to fall into pride over it, our fasting is of no benefit. But the cure to that ailment is to humble ourselves, not to give up fasting. Indeed "Let us make haste to follow the Pharisee in his virtues and to emulate the Publican in his humility, and let us hate what is wrong in each of them: foolish pride and the defilement of transgressions"