People are created with dualistic natures. We think in terms of male/female, joy/sorrow, light/dark, etc. This causes much grief, as we often feel caught in a world and circumstances that we have no control over. Many yogis solve this problem by withdrawing from "the material world" physically, isolating themselves, and practicing severe physical hardships to "kill" their physical desires. Tantra, however, recognizes this world as a gateway to other realms, and acknowledges human nature, fleshly pleasures, and human emotions as valid. Tantra does not say "withdraw from the world - flesh is evil - all is Maya". Rather, we seek liberation, with a sincere and pure heart. We seek to enjoy the pleasures of the world we live in, always keeping alive the spiritual intent. We seek thus to live in the bliss of pure being: "I and my father are one", or "thou art that".
We were created with physical instincts, natural urges and actual needs, and so these should not be thought of as 'evil' or something to get rid of. If you don't eat, you will die. So, rather than seeking to control your physical body through severe fasting and starvation, the Tantras teach that one must nourish the body, and that the act of eating can become a sacrament in itself.
Similarly, the repression of sexual desires may lead to eruption of the sexual energy in other ways. Tantra does not condemn those who practice celibacy as a way of channelling the energy, but that energy can also be channelled during lovemaking. The intent elevates the merely physical to the sublime.
If you don't eat, you will die. If no one has sex, the entire human race will die. Rather than attempting to 'master the flesh' by punishing it or ignoring it, master it by using it as it was given to you, freely and naturally, by using it as a vehicle to spirituality.
The body is a temple, to the deity within. It can be used for worship. So we do not despise the flesh, or wish it gone.
There is a fine line between pleasure and bliss, and Tantra recognizes both as valid. Partake of pleasure, and realize bliss.
Tantric texts were written with three levels of meaning: the literal, the allegorical, and the mystical. The intent was simply, in a climate of religious and cultural bigotry, to separate the sincere from the curious. Tantra is non-sectarian: it allows any follower of any path or religion to access its secrets, so long as that follower is sincere. External worship leads to internal worship. Internal worship purifies the mind. Purity of mind intensifies concentration and meditation. When meditation is ripe, Samadhi ensues, the the highest bliss is attained.
Even those who exploit the Tantric teachings as license for acts of pleasure in and of themselves, and those who use it merely as a form of sexual magick, are recognised as having the potential for growth. The Tantratattva says:
From hankering after sensual pleasure or power in the form of money, fame, popularity, orgiastic sex, one gradually lifts his eyes upward and wonders about the pleasure and power of the unseen world. He longs for it, seeks after its acquisition. And when he obtains but the smallest morsel of it, he at once realizes the transity of worldly desires. He forthwith parts with them as a serpent sheds its dead skin.
When a Tantric practitioner chooses to become celibate, to concentrate on what he has learned through sexual union, this is honest renunciation. As Krishna says, in the Bhagavad Gita:
The abstinent run away from what they desire, but carry their desires with them. When a man enters reality, he leaves his desires behind him.
No distinction is made between the white (solo) Tantric practitioner, the red (coupled) Tantric practitioner, and the celibate. The celibate is not considered in any way superior to those who continue the process of spiritual evolution through Tantric sexual union. It is all a matter of the will of the individual self: so long as the will pursues evolution, evolution will be granted.
adapted from: http://beyond-the-illusion.com/files/Occult/Tantra/Tantric_path.txt by D. Yogini Padma Ushas Suryananda