For Christian pastor Larry Tomczak, US President Barack Obama is guilty of wrecking America's moral fibre.

In an opinion piece entitled "Something Catastrophic Is Coming: Should We Tune Out?" published on the Charisma News website, Tomczak wrote about the bleak future facing America.

"A perfect storm is developing and this is not some surreal conspiracy theory," said Tomczak, who has authored eight bestsellers.

"It is no exaggeration to say America is at a crossroads ... in a meltdown ... at a tipping point ... experiencing unprecedented changes ... observing our president act like a one-man wrecking crew to bring about his fundamental transformation of America," he said.

The Christian pastor particularly criticised Obama's stand on controversial issues such as same-sex marriage, the nuclear deal with Iran, the threat posed by Russia, and abortion.

"Russia is our greatest threat—nah, it's global warming. Same-sex marriage! Light up the White House! 'I can't run again but if I could, I'd win!'," Tomczak said, quoting some of Obama's controversial statements.

In the face of this so-called "perfect storm," Tomczak also called on Christians to be extra vigilant and prayerful.

"Considering the above, it is not a time to check out of the game but re-consecrate ourselves to prayer and be ready for whatever will unfold in the months ahead. I sense dramatic change coming, judgments and severe economic upheaval," the Christian pastor said.

"Returning from Washington, D.C., where I lived for 24 years, you can pick up the whiff of something imminent in the air," he added.

He also called on Christians in America "to stay informed in this generation."

"While the biblical principle of balance and moderation is always in order, are there not seasons where desperate times require desperate measures? Just as birth pangs increase in intensity and frequency until delivery, are there not unique times in history when more is required of us because the pace is quickening and it's imperative as 'watchmen on the wall' to remain vigilant? Could we be in just such a time?" Tomczak asked.