The only declared contender for the Lib Dem leadership told Sky's Sophy Ridge On Sunday the leader's position was a "perfectly fair one" but he should have "put these to one side" while enacting public policy.
Sir Vince, who is widely expected to replace Mr Farron as leader said he had done "a great job" in helping the Lib Dems recover from the 2015 election and rebuild its party membership.
However, he added: "He did, as he himself acknowledged, not handle that whole issue very well at reconciling his own personal faith with his public positions on gay rights and other issues.
The evangelical leader announced his resignation last month, saying he could not face continued questions over his beliefs. He said: "A better, wiser person than me may have been able to deal with this more successfully, to have remained faithful to Christ while leading a political party in the current environment.
"To be a political leader - especially of a progressive, liberal party in 2017 - and to live as a committed Christian, to hold faithfully to the Bible's teaching, has felt impossible for me.
Mr Farron faced repeated questioning during the 2017 General Election campaign over his views on homosexuality. Expressing his support for LGBT rights and equal marriage, he initially declined to explain his stance on gay sex.
After provoking a wave of criticism, Mr Farron later clarified his opinion, explaining he did not believe homosexuality was a sin.
The Archbishop of Canterbury called Mr Farron "honourable and decent" and The Archbishop of York described the Liberal Democrat's leader's critics as "cynics" and "tormentors".
In a strong reprimand in The Daily Telegraph, Archbishop John Sentamu said that the "hounding" of Tim Farron by the media before the elections was unacceptable. He said they "should be ashamed of themselves" and declared Mr Farron's resignation was a thing of regret.
