Remember first of all that the Ante-Nicene fathers, as valuable and authoratative as they are, are not infallible. The Second Council of Nicaea (an Ecumenical Council) in its decrees against those who deny the place of images, icons, and statues in the Chuch is. Before doubting the validity of icons in the Christian Church, I would read the writings of St. John of Damascus (8th century), the decrees of Second Nicebne Council, the Second Vatican Council, and most of all, the Old Testament’s descriptions of the Tabernacle, Solomonic Temple, and Herodian Temple, all of which were lavishly adored with divinely-approved, cultic/religious, graven imagery.
That being said, I point you to several facts. First of all, the Early Christian writers that speak against the place of imagery in the Church do not represent the univeral conviction of the early Church. The disciples worshipped on the courts of the imagery-laden first temple in the book of Acts. The Catacombs are full of Christian engravings, frescoes and statuettes from the Ante-Nicene period (earliest examples date to about AD 200). The earliest Christian Church yet excavated (in Dura-Europas, c. AD 250) is covered wall-to-wall in religious images and portraits. Therefore, be careful to avoid calling their opinions “universal” by any stretch of the imagination.
Rather, Catholics acknowledge their opinions to be misinterpetations of the commandment against graven images, one shared by many in contemporary Judaism (again not universally). It is, however, a failed thesis: often raised, always finally condemned by the Church. Tertullian, for example, was forced to allegorically interpret the Old Testament descriptions of the Old Testament Temple decorations in order to deny their literal veracity, again, a flawed conclusion. But, it is a thesis that often arises when Christanity is forced to distinguishitself from its surroundings.
The Early Christian rejection of images was encouraged, as noted above, by a deep-seated desire to distinguish themselves from the pagan world, especially in imperial apologies. They attempted to present themselves as utterly above paganism, and so they may have exaggerated their claims to sharpen the distinction. Or, they may smply have been mistaken. The former desire was the motivation behind Byzantine iconoclasm in the 8th century (wanting to appease Islam), Protestant iconoclasm in Europe (wanting to create a “pure” faith, uncorrupted by “paganism”), and Anabaptist/Amish iconocasm (trying to escape this “wicked world”), among others. In each case,it has bred a conviction that cannot be substantiated theologically, and represents a mistaken and inconsistent interpretation of the Biblical view of images (again, reading the above defenses of the Catholic/Orthodox use of icons is of inestimable value).
The same applies to “temple, altars, and incense.” The Church may establish temples and lavishly decrate them as the Jews built synagogues and Temples. Simply because the Church, as an illegal sect, was not legally allowed to construct many churches in the Ante-Nicene period does not mean that Chritianitis to be championed as the anti-Temple religion (an exaggerated claim of these writers).
Usually these positions were also adavanced by a will to champion Christianity as the “spriritual” religion over and against the “material, base” practices of paganism. However, the Church has sharply condemned similar views which at their base are Manichaean: rejecting the value of the material. No, the material as well as the spiritual are to be embraced, as exemplified by the Incarnation. Incense need not be prayer alone, but literal incense may fill our churches as a symbol of prayer and honorific sign of worship. The spiritual nature of Christian worship does not mean we are anti-literal-altar (Ignatius of Antioch uses the term to describe the Eucharistic table, as do other Ante-Nicene fathers). Although we are aware (as the Latin rite liturgy states) that there is an altar in heaven, that does not mean that the Eucharistic table on earth, which supports the Eucharistic sacrifice is not also a spiritual altar.
In short, with the Ante-Nicene fathers, be aware that they are not infallible, and had polemical reasons for making claims that the entire Church would not have endorsed. Don’t let that dampen their view of them, I believe in most cases, these were honest mistakes, or perhaps they were phrasing their positions in ways that are actually being misread today. Either way, I have had to deal with the same issues on my road to conversion… I wish you well in your studies.