Generally speaking, many Hindus will respect all religions. They may be initiated by a Vedic guru, devoutly practice yoga, attend the temple regularly, yet still go to see some Christian preacher, or Buddhist teacher, or even hear an Islamic Imam talk about God. They may do this with the idea of attaining new insights, yet still not consider themselves falling away from their own path or converting to a different religion.
Yet, if a Christian or Muslim would do such a thing as participate in an alternative religion, or even a different sect from which they belong, they may be considered sinful and apostates, or at least hypocrites and deserving of some punishment. But such narrow-mindedness hardly touches the person following the Vedic path.