Skeptical of Al Qaeda, who beheaded an Iraqi couple in front of their children for being infidels because they "wore western trousers" and did not pray.
Determinations based upon the make or material of one's clothes rather than the faith and beliefs of one's heart are the result and display of legalism (in this case, resulting from cultural/religious bias & brainwashing), not spirituality.
Not only that, but based on "wearing western trousers" being part of the criteria for proving oneself an infidel, would not the 9-11 high-jackers be infidels (or partial infidels, or at least participating in the practice of infidels), not to mention scores of Muslims living in the West today!
1 Cor 2:12-13 "We have not received the spirit of the world but the Spirit who is from God, that we may understand what God has freely given us. This is what we speak, not in words taught us by human wisdom but in words taught by the Spirit, expressing spiritual truths in spiritual words."