The CDWDS looks at the homily, though I don’t think much of thr accuracy of their assessment of the situation. Let’s read that the curia starts off on the right foot:
[64.] The homily, which is given in the course of the celebration of Holy Mass and is a part of the Liturgy itself, [Cf. Code of Canon Law 767 §1] “should ordinarily be given by the Priest celebrant himself. He may entrust it to a concelebrating Priest or occasionally, according to circumstances, to a Deacon, but never to a layperson. [Cf. GIRM 66; cf. also the Code of Canon Law 6, §1, 2; also 767 §1, regarding which other noteworthy prescriptions may be found in Congregation for the Clergy et al., Instruction, Ecclesiae de mysterio, Practical Provisions, art. 3 § 1: AAS 89 (1997) p. 865] In particular cases and for a just cause, the homily may even be given by a Bishop or a Priest who is present at the celebration but cannot concelebrate”. [GIRM 66; cf. also the Code of Canon Law 767 §1]
It gets a bit wobbly here:
[65.] It should be borne in mind that any previous norm that may have admitted non-ordained faithful to give the homily during the eucharistic celebration is to be considered abrogated by the norm of canon 767 §1. [Cf. Ecclesiae de mysterio, Practical Provisions 3 §1; cf. also the Code of Canon Law 6 §1, 2; Pontifical Commission for the Authentic Interpretation of the Code of Canon Law, Response to dubium, 20 June 1987: AAS 79 (1987) p. 1249] This practice is reprobated, so that it cannot be permitted to attain the force of custom.
Canons 766 & 767 treat the matter of preaching, and as of 1983, provided for the local bishop to oversee the matter of preaching for his diocese, including lay people. I’m aware that canonists (see the footnote) were not fond of the wiggle room provided here.
No practicing for seminarians, either:
[66.] The prohibition of the admission of laypersons to preach within the Mass applies also to seminarians, students of theological disciplines, and those who have assumed the function of those known as “pastoral assistants”; nor is there to be any exception for any other kind of layperson, or group, or community, or association. [Cf. Ecclesiae de mysterio, Practical Provisions 3 § 1]
This is probably quite shortsighted, especially for communities of religious women who have no male members, and for parishes without resident pastors. Preaching should be determined by charism and properly monitored by the bishop.
The CDWDS defines a homily:
[67.] Particular care is to be taken so that the homily is firmly based upon the mysteries of salvation, expounding the mysteries of the Faith and the norms of Christian life from the biblical readings and liturgical texts throughout the course of the liturgical year and providing commentary on the texts of the Ordinary or the Proper of the Mass, or of some other rite of the Church. [Cf. Ecumenical Council of Trent, Session XXII, 17 September 1562, on the Most Holy Sacrifice of the Mass, Chapter 8: DS 1749; GIRM 65] It is clear that all interpretations of Sacred Scripture are to be referred back to Christ himself as the one upon whom the entire economy of salvation hinges, though this should be done in light of the specific context of the liturgical celebration. In the homily to be given, care is to be taken so that the light of Christ may shine upon life’s events. Even so, this is to be done so as not to obscure the true and unadulterated word of God: for instance, treating only of politics or profane subjects, or drawing upon notions derived from contemporary pseudo-religious currents as a source.[Cf. Pope John Paul II, Allocution to a number of Bishops from the United States of America who had come to Rome for a visit “ad Limina Apostolorum”, 28 May 1993, n. 2: AAS 86 (1994) p. 330]
RS 67 is actually a quite useful and constructive section: focus on Christ. It’s quite evangelical, and it rather limits the temptations from the fringes to preach in certain ways that do not explicitly lead to Christ. Though some might interpret politics or psychology as being derived from Christ and his teachings.
Bishops may no longer oversee who preaches, but they are still responsible for formation of clergy:
[68.] The diocesan Bishop must diligently oversee the preaching of the homily,[Cf. Code of Canon Law 386 §1] also publishing norms and distributing guidelines and auxiliary tools to the sacred ministers, and promoting meetings and other projects for this purpose so that they may have the opportunity to consider the nature of the homily more precisely and find help in its preparation.
Whew! After all that homiletic stuff, let’s consider the Creed:
[69.] In Holy Mass as well as in other celebrations of the Sacred Liturgy, no Creed or Profession of Faith is to be introduced which is not found in the duly approved liturgical books.
Comments, especially on the homily, which I know we’ve covered on this site in the past.