We as Christians often disagree with one another about many things, but everyone who has been truly converted has at least the following core convictions in common:
1.) They know the truths they heard about in the gospel are real. It’s not that they don’t ever doubt or have questions. It is just that deep in their gut they are convinced that what the Bible says about God, Jesus, this world, themselves, and salvation is right and beautiful and excellent and they are seeking to place their whole lives in Jesus’ hands as a result and live completely for Him.
2.) They believe God’s right to punish sinners. They get that. And as a result, they are not going to spend their lives quarreling about it. (Though they might quarrel with themselves about wanting to quarrel about it!) But ultimately they are at peace with God being God and God being holy and want to spend their lives glorifying Him for it instead of questioning Him about it.
3.) They have caught a glimpse of the beauty of Jesus Christ as He’s revealed in the gospel and that glimpse alone was enough to make them sure He is better than anything else in this whole world. They are “convinced in their mind that Christ is an excellent Savior and a sufficient Savior and their heart is inclined to Jesus as the most lovely person, more lovely than any other object on earth and as a lovely Savior, and that the way of salvation by free grace and Christ’s worthiness is the only and most perfect way of being saved, so that their soul longs for Jesus as the Savior for them.
4.) They have been humbled by their own sinfulness. I mean really humbled to the point where they know beyond a shadow of a doubt that if they are going to be saved, it’s going to be all God, not anything they bring to the table. If you try to get them to glory in their works or their salvation, they think you are crazy, because they know who gets the credit, and they want to spend the rest of their lives giving that credit and praise to Him.*
(Paraphrase of Jonathan Edwards, 2 Corinthians 13:5, “Persons ought not to rest ignorant and unresolved about their own state whether they be real Christians or no.”)