I'll Think About God Later.

The apostle Paul had been arrested and thrown in prison. The leaders of the Jews wanted him dead, but Paul was a Roman citizen so the Romans took charge. One day he was brought before Felix, the procruator of Judea.

"Some days later Felix arrived with Drusilla, his wife who was a Jewess, and sent for Paul and heard him speak about faith in Christ Jesus." Acts 24:24

What a wonderful opportunity for Paul to lift up the life and death of Jesus. Paul cared about Felix and his wife; he wanted them to accept Christ and be saved.

Ellicott's Commentary for English Readers
Drusilla. She was, according to Josephus, the daughter of Herod Agrippa I., who "killed James with the sword" and died shortly afterwards. She was first the wife of Azizus, King of Emesa; but Felix, becoming enamored of her on account of her singular beauty, employed a certain magician, a Jew named Simon, to entice her away from her husband, and persuade her to marry him, contrary, as Josephus says, to the institutions of her country. She perished, with Agrippa, her only son by Felix, in the eruption of Vesuvius, in the reign of Titus

"But as he was discussing righteousness, self-control and the judgment to come, Felix became frightened and said, "Go away for the present, and when I find time I will summon you."

Paul spoke of righteousness, which meant he was explaining the way a good person would live out his life in Jesus. 
He spoke of self-control, which it seems from Felix's past, was not one his attributes. 
He spoke of the judgement to come, when all people will be judged by the works they have done. 

All this frightened Felix. He obviously felt himself to be far from righteous and was worried that he may one day be judged by God.

MacLaren's Expositions
Felix and his brother had been favorite slaves of the Emperor, and so had won great power at court. At the date of this incident he had been for some five or six years the procurator of the Roman province of Judaea; and how he used his power the historian Tacitus tells us in one of his bitter sentences, in which he says, ‘He wielded his kingly authority with the spirit of a slave, in all cruelty and lust.’

Jamieson-Fausset-Brown Bible Commentary
Felix trembled—and no wonder. For, on the testimony of Tacitus, the Roman Annalist [Annals, 9; 12.54], he ruled with a mixture of cruelty, lust, and servility, and relying on the influence of his brother Pallas at court, he thought himself at liberty to commit every sort of crime with impunity. 

We do not know if Felix and his wife ever gave their lives to God; we only know what Felix said to Paul, that he didn't want to think about these things now, maybe later.

It isn't safe to put off our salvation. We are human, we could die at any moment. Also, after putting God off for months and years, we may become so dead to what is right that we may never hear his voice in our hearts again. This is what Jesus meant when he said, ""Therefore I say to you, any sin and blasphemy shall be forgiven people, but blasphemy against the Spirit shall not be forgiven."  Matthew 12:31

If we continually turn away from the Spirit of God then nothing can save us.