Let's begin with reflection
As a way into what other faiths believe, and to explore how Christian faith can be deepened and enriched by encounters with people of different religions, individuals or groups could use the materials produced by Churches Together in Britain and Ireland as a Lent resource for 2017. The link is https://ctbi.org.uk/lent-course-2017/
A good starting point for thinking about dialogue is ‘Acting in God’s Love – Christian witness in a multi-religious world’, available as a download from Churches Together in Britain and Ireland: https://ctbi.org.uk/wp-content/uploads/2017/11/IFTAG-study-guide.pdf.
Helpful ground rules for meeting with other faiths
Simple ‘ground rules’ for meeting with other faiths can be found in the IFN code, ‘Building good relations with people of different faiths and beliefs’. This was last revised in Dec 2017 and can be found here: https://www.interfaith.org.uk/uploads/IFN_Code_2017.pdf
How to meet with other faiths
As a more ‘how to’ resource, IFN also produce ‘Let’s talk: practical pointers for inter faith dialogue' - https://www.interfaith.org.uk/uploads/LetsTalk2017web.pdf
Essential reading
Poorly-directed attempts to proselytise or ‘convert’ members of other faiths risk giving considerable offence. Essential reading are the Ethical Guidelines produced by the Christian Muslim Forum: http://www.christianmuslimforum.org/downloads/Ethical_Guidelines_for_Witness.pdf
Some Important Guidance
Much and more detailed guidance has been produced by the World Council of Churches. The report ‘Christian Witness in a multi-religious world’, from WCC with the Pontifical Council for Interreligious Dialogue and the World Evangelical Alliance, is a simple and important document: https://www.oikoumene.org/en/resources/documents/wcc-programmes/interreligious-dialogue-and-cooperation/christian-identity-in-pluralistic-societies/christian-witness-in-a-multi-religious-world/@@download/file/ChristianWitness_recommendations.pdf
A more detailed report, ‘Guidelines on Dialogue with People of Living Faiths and Ideologies’, dates from 1979 and is still available here: https://www.oikoumene.org/en/resources/documents/wcc-programmes/interreligious-dialogue-and-cooperation .
A 2004 update was given by the paper https://www.oikoumene.org/en/resources/documents/wcc-programmes/interreligious-dialogue-and-cooperation/interreligious-trust-and-respect/ecumenical-considerations-for-dialogue-and-relations-with-people-of-other-religions .
For other WCC papers, see the Inter Faith Resources webpage.