God's word in the Bible is good enough for me. His word says keep the feast of unleavened bread - that's what I am going to do.
And this is in the NEW TESTAMENT.
No, he says "Christ, our Passover, was sacrificed for us. Therefore let us keep the feast ... with the unleavened bread of sincerity and truth." He's talking about the Catholic Mass, if any feast at all (Chrysostom thinks that the leaven v. unleavened is simply a metaphor, and this interpretation has probability: see his homilies on I Cor.)
7 Purge out the old leaven, that you may be a new paste, as you are unleavened. For Christ our pasch is sacrificed.
8 Therefore, let us feast, not with the old leaven, nor with the leaven of malice and wickedness: but with the unleavened bread of sincerity and truth.
9 I wrote to you in an epistle not to keep company with fornicators.
10 I mean not with the fornicators of this world or with the covetous or the extortioners or the servers of idols: otherwise you must needs go out of this world.
11 But now I have written to you, not to keep company, if any man that is named a brother be a fornicator or covetous or a server of idols or a railer or a drunkard or an extortioner: with such a one, not so much as to eat.
12 For what have I to do to judge them that are without? Do not you judge them that are within?
13 For them that are without, God will judge. Put away the evil one from among yourselves.
v. 8 is showing the reason for v. 9-13: "I have written to you ... with such a one, not so much as to eat." In other words, they were to be excluded from communion.
Your interpretation makes no sense. Why would Paul have thrown a command to keep the Feast of Unleavened Bread into his discussion of the measures to take against the fornicator?
Yup. Good enough for me too.