There are two main arguments against it. First, the ICOC leadership explained to me that Matt. 28:19–20 establishes that one must be a “disciple” before one is baptized on the following basis. Matt: 28:19 in the NIV reads, “Therefore go and make disciples of all nations, baptizing them in the name of the Father . . .” Note the italicized “them.” It is said that the “them” refers to “disciples” in the phrase “make disciples,” and therefore one must be a “disciple” before one is baptized and becomes a Christian. However such an interpretation is based on entirely on one English translation and with a total ignorance of the Greek behind English translations.
Notice the Young’s literal translations doesn’t say go “make disciples,” but go “disciple all the nations.” If we are to “go and disciple all the nations, and baptize them,” who is the “them” referring to? Is it disciples? “Them” is a pronoun and its antecedent must be another pronoun or noun. It can’t be a verb. There is one Greek word to connote the verbal idea of discipling, which NIV translators have expressed as “making disciples.” So here “disciples” is part of the action of disciple making expressed as an imperative, so the ‘them’ cannot grammatically refer to “disciples.” Interestingly, the “them” is a masculine pronoun and “nations” is a noun in the neuter, so “nations” is not the antecedent because in Greek a pronoun will agree in grammatical sex with its antecedent. You don’t baptize nations, but people who comprise a nation. So the pronoun is silent but understood. Greeks often abbreviate their thought, as writing was expensive and time consuming. The implied sense is, “make disciples of (the people) of all nations, baptizing them (the people of the nations).” That is, people of nations become disciples by being baptized and being taught all the commands to be obeyed. This verse is describing how a disciple is made, and it occurs by a two-step process of (1) being baptized and (2) being taught to observe all God’s commands.
Secondly, the ICOC's requirement that one becomes a "disciple" before one is baptized is to force people to live righteously by their own strength before they receive the power of the Holy Spirit to overcome sin, and therefore such actions of proving one is a disciple before baptism amounts to having to obtain holiness through one's own works rather than depending on the Spirit. Notice that the Great Commission reads that it is AFTER baptism that people are to be taught how to observe or obey the commands, not before, as the ICOC teaches.
The ICOC's doctrine of 'baptizing disciples" is incompatible with the "sanctifying work of the Holy Spirit" (2 Thes. 2:13). The Spirit gives us power over sin by giving us another way to feed ourselves rather than through the flesh. In baptism, we don't put to death our flesh, but our "old self" (Rom. 6:6) that used to rely on the flesh to satisfy ourselves. Because we have another way to feed ourselves, and one that will actually meet our deepest needs, we are able to deny the flesh daily and live off the Spirit. Thus, this crucifying the "old self" is not a one-time event that occurs at baptism, but is to be ongoing in a person's Christian walk.
Those who do not have the Spirit have no other way to feed themselves and so their denial produces a starvation in which they eventually revert back to an enslavement in sin or swap sinful addictions. People can choose not to avail themselves of living by the Spirit after receiving it in baptism, and in doing so will not live any different from those who are unbaptized. I believe this has largely occurred because many in the church walk around in ignorance about the relationship between the Holy Spirit and sanctification. Historically, far more attention has been given to discussions of God the Father and the Son, and very little on the work of the Holy Spirit in regard to sanctification.
Once people have the Spirit it baptism, which itself is an action of trust, their actions of holiness after baptism are not works, but actions of trust--ones that are dependent upon and made possible by the Holy Spirit who came to indwell people from that point forward. If a church insists on baptism, but has no teaching about the Holy Spirit in regard to sanctification, then structures to control sin must be achieved through human regulations imposed by church leaders on members through tactics of guilt, peer pressure, or psychological manipulation, and/or through members’ own self-imposition of will power. This is where much of the church abuse in the ICOC has historically arisen.