Gary Streeter, who sits on a parliamentary group which monitors North Korea, said an apparent willingness by Kim Jong-Un to surrender his nuclear weapons programme could be a farce.
The Conservative representative for South West Devon told Premier: "We should pray for these talks to become significant.
"Of course, it may be that the North Korean leadership are just posturing but sometimes, when you open the door, you can't control the forces that then rush through it."
Earlier on Friday, Kim Jong-Un and Moon Jae-in stood side by side on their countries' border to announce an agreement to rid their peninsula of nuclear weapons and not return to the tensions of the past.
Mr Streeter added: "We are going to need a time in the future when the people of North Korea will have to find the courage to rise up and overthrow their oppressors.
"I think we should be praying that they find that courage and the inspiration to do that."
The two leaders each shovelled soil taken from both nations onto the roots of a symbolic pine tree planted on the frontier dividing their two nations.
Open Doors, which smuggles Christian literature into North Korea and has repeatedly warned over many years the nations is the toughest place on earth to be a believer, encouraged people to pray for its heavily-persecuted Church.
Spokesperson, Beth Fuller said: "For the Christians in North Korea to see these talks between North and South Korea will be a real encouragement for them, for people who've perhaps been praying for years that reunification will come.
"The Church in North Korea, despite the horrific persecution they face, actually really has incredible hope for the future - and really has a vision that one day they will be reunited with the Church in South Korea."
Friday's meeting marks the first time a North Korean leader has entered South Korea in more than 50 years. It comes before a scheduled meeting between Kim Jong-Un and Donald Trump.
Listen to Gary Streeter and Beth Fuller speaking with Premier's Alex Williams here:
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