In some ways the Christian message is really simple to explain. In other ways it’s really not.
e.g. the following…
It’s impossible to overstate God’s righteous anger at our sin1… but it’s also impossible to over-emphasise his love2 towards us and how pleased he is to welcome repentant3 sinners into his family as adopted children.†
Christians want to boldly and authoritatively proclaim both of the above as objectively true (the implication being that contradictory beliefs are false)… but at the same time we need to remain humble, in light of the facts that a) our knowledge of the truth remains imperfect, and b) any knowledge we do have of the truth has been given freely to us by God, so we have nothing to boast about.
Christians should also remain humble while speaking against sinful lifestyles because a) it’s only thanks to God’s grace toward us that we are any less sinful than anyone else, and b) we do still sin, and the more knowledge we have of God, the more guilt our sin deserves… but on the other hand, if we speak and act as if our knowledge of God makes no difference to the way we live, we will dishonour God, and non-Christians will see no point in considering the possibility of “following Christ” themselves.
I’m reluctant to say we need to strike a balance on each of these, because I think what people normally mean by that is something like “we need to be careful not to emphasise grace too much, in case people get the impression their sins don’t matter” or “we shouldn’t put too much emphasis on God’s wrath against those who break his law, in case people think they have to earn His acceptance by working hard at obedience”. While those are both valid concerns, I think the actual solution is not to limit how strongly we emphasise grace and try to carefully balance it out with an equally limited amount of law, but rather to throw as much biblical weight as we possibly can on both sides of the scales. The more deeply we understand God’s hatred of sin, the more we will appreciate his grace, and the more deeply we understand his grace, the more we will be motivated to work to eradicate sin from our lives.
1 In case anyone reading this is not sure what I mean by sin: it is disobedience of God’s law. This law is summarised as “You shall love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind, and your neighbour as yourself.” The just punishment for breaking this law is to be cut off from God, aka death.
2 It should be noted that, contrary to the popular understanding in our culture, love does not equal unconditional affirmation; rather, it involves acting in the best interests of the beloved, even if that sometimes means telling them that, although something might give them pleasure now, in the long run it will do them more harm than good.
3 It should also be noted that repentance (turning back to God and away from sinful practices) does not cause God to accept us, but is an inevitable effect of acceptance.
†In case anyone reading this is not sure how God can both be angry at our sin and simultaneously love us as adopted children: it’s because God created us for the purpose of demonstrating the immense depths of his love towards us, and he did this by taking the punishment that our sin deserves on himself when Jesus died on the cross. So we get forgiveness and God gets to display the amazingness of his love.