A common way unbelievers deflect objections is to ask why apologists focus so much on their religion and not as much on others. Apologists are even accused of "obsession" with their specialist area, which apparently becomes an argument for that religion.
But the truth is, the saying "knowledge is power" is 100% true, and 100% Biblical. It is foolish to speak about things you don't know (Proverbs 18:13), and so an apologist should never address a religion he does not know. However, after carefully considering a religion, as Paul did in Acts 17, it becomes easy to address it, and lead its followers to Christ.
One example is Islam. Muslims will often complain that anti-Islamic apologists are "persecuting" them for talking about Islam so often. For example, I once saw a live stream where a Muslim asked why David Wood talks about Islam so much, but doesn't talk about Hinduism. Wood's answer was fairly simple: There are over a billion Muslims, there aren't so many Hindus. Thus, by addressing Islam, Wood expands his Gospel outreach far more than he would if he spoke about Hinduism. Personally, my reason for not addressing Hinduism is I know nothing about Hinduism. I do, however, have a reasonable grasp on Islam. This is especially thanks to the aforementioned David Wood, so if you'd like to learn how to reach Muslims, I strongly recommend his material.
One fundamental thing in Islam is its rejection of the Trinity, with a special emphasis on denying the divinity of the Son. In fact, Allah is a father to no one, and Jesus is certainly no exception. Nevertheless, Islam does acknowledge Judeo Christianity. In fact, the Qur'an declares that Jesus and the Jewish prophets were, indeed, prophets sent by God. It also affirms the inspiration, preservation and authority of the Bible. Knowing this, we can look at what the Bible says and see if it agrees with Islam. If it doesn't, Islam is false.
Needless to say, the Bible alone is sufficient to prove the Trinity. However, we need not stop there. We can actually compare the Bible and the Qur'an to show that actually, even according to Islam, Jesus must be God.
In Qur'an 22:56, "Allah" tells us that he will be the final judge. Yet, in John 5:22, Jesus tells us that the Father judges no one, but rather, He will judge all. From these facts, we can construct the following syllogism:
Premise 1: Only Allah will judge all.
Premise 2: Only Jesus judges all.
Conclusion: Jesus is Allah.
Thus we see the power of knowledge. It is, unfortunately, impractical to study all the world's religions. And of course, by nature, when you become a jack of all trades, you inevitably become a master of none. However, when you do know enough about a given religion, you have everything you need to reach those who follow it with the truth of the Gospel.