Andrea Leadsom has said she "didn't really like" laws to allow gay marriage because they hurt "many Christians".

The contender for Conservative party leadership – and therefore Prime Minister – said marriage "in a Biblical sense" was between a man and a woman according to most Christians. She added she would have preferred marriage to have remained "a Christian service" with civil partnerships available to both heterosexual and gay couples.

In an interview after a speech in Westminster urging support for her leadership bid, the committed Christian said she was concerned about the "potential compulsion" the law put on the Church of England.

She told ITV News: "I believe the love of same-sex couples is as every bit as valuable that of opposite sex couples – absolutely committed to that. But nevertheless, my own view actually, is that marriage in the biblical sense is very clearly from the many, many Christians who wrote to me on this subject – in their opinion – can only be between a man and a woman."

She continued: "But what I do think is that I would have preferred for civil partnerships to be available to heterosexual and gay couples and for marriage to have a remained a Christian service for men and women who wanted to commit in the eyes of God.

"Civil partnerships are called marriage as well. As in registry offices marriages are still marriages. The concern I had was the potential compulsion for the Church of England so I don't think that the Anglican Church should be forced down a route where many Christians aren't comfortable about it. My own view on it was to positively abstain.

"This is not about do I consider gay couples to be any less worthy of marriage than heterosexual couples – not at all, it's exactly the same. The issue is one I have around the consequences, the very clear hurt caused to many Christians who felt that marriage in the Church could only be between a man a woman. I think we've muddled the terms of marriage, civil partnership, church etc. I would have liked that to have been clarified. I didn't really like the legislation – that was the problem. But I absolutely support gay marriage."

Leadsom, a junior energy minister, is down to the final two in the leadership contest. Members of the Conservative Party now have a straight choice between her and Theresa May.

The interview with ITV came after a speech where Leadsom promised to "banish the pessimists" over the UK's future outside the European Union. But Leadsom refused to take questions after being accused of exaggerating claims on her CV.